An alternative way to assist the suspension of disbelief, instead of giving a plausible explanation for why it works, is to instead describe in detail what it does. Describe all of its quirks and limitations.

This works well narratively because everyone on the ship will know in detail what it feels like when the gravity generator is on the fritz but few will actually understand the gravitomagnetic effect it uses to bend space-time around itself.

You can be creative and give it a lot of different problems.

For example, in Star Trek: Enterprise, the human engineers haven't figured out how to generate a completely uniform gravity field, and there's a small space in the Enterprise where it goes the wrong direction; in one room you can jump up and sit on the ceiling.

Other possibilities:

Does it taper off gradually outside the ship? If it changes a lot over a short distance, large delicate objects could be snapped in two by the relative difference in gravity at each end of the object when falling out of the field. This could be particularly impractical on a smaller ship with a smaller artificial gravity field.

Does the field itself have significant inertia? Does it have angular momentum like a massive gyroscope? It could take a lot of extra energy to accelerate or rotate the ship when the gravity generator is on. Maybe space tugboats and space marine boarding craft don't have gravity generators, to make them nimble enough to manoeuvre around other craft.

Is it physically huge, costly, or very energy intensive? It might not make practical or economic sense to include them on small vessels.

If it doesn't also propel the ship, and the gravity is pointing in one direction over most of the ship, then something on the ship has to be pushed up with a force equal to the force pushing everything else down. Possibly the generator itself. Strong structural beams would have to anchor the gravity generator to every section of the ship, or the ship would fall apart. To minimise bad leverage on these beams, a very large single generator ship might be shaped like a skyscraper with the generator near the bottom. Large vessels in other shapes would need either multiple gravity generators to distribute the load across the structure, or to have gravity pointing in opposite directions in different sections of the ship.

Does the gravity field's shape or strength change when the generator is rotated or accelerated? This could provide some light comedy with people spilling their coffee at one end of the ship when it turns around, or it could be a serious limitation to how fast a ship can manoeuvre with the gravity generator on without tearing itself apart.

An alternative way to assist the suspension of disbelief, instead of giving a plausible explanation for why it works, is to instead describe in detail what it does. Describe all of its quirks and limitations.

This works well narratively because everyone on the ship will know in detail what it feels like when the gravity generator is on the fritz but few will actually understand the gravitomagnetic effect it uses to bend space-time around itself.

You can be creative and give it a lot of different problems.

For example, in Star Trek: Enterprise, the human engineers haven't figured out how to generate a completely uniform gravity field, and there's a small space in the Enterprise where it goes the wrong direction; in one room you can jump up and sit on the ceiling.

Other possibilities:

Does it taper off gradually outside the ship? If it changes a lot over a short distance, large delicate objects could be snapped in two by the relative difference in gravity at each end of the object when falling out of the field. This could be particularly impractical on a smaller ship with a smaller artificial gravity field.

Does it switch on instantly, dangerously throwing floating objects to the floor? Or does it take an annoyingly long time to spin up to full power?

Does the field itself have significant inertia? Does it have angular momentum like a massive gyroscope? It could take a lot of extra energy to accelerate or rotate the ship when the gravity generator is on. Maybe space tugboats and space marine boarding craft don't have gravity generators, to make them nimble enough to manoeuvre around other craft.

Is it physically huge, costly, or very energy intensive? It might not make practical or economic sense to include them on small vessels.

If it doesn't also propel the ship, and the gravity is pointing in one direction over most of the ship, then something on the ship has to be pushed up with a force equal to the force pushing everything else down. Possibly the generator itself. Strong structural beams would have to anchor the gravity generator to every section of the ship, or the ship would fall apart. To minimise bad leverage on these beams, a very large single generator ship might be shaped like a skyscraper with the generator near the bottom. Large vessels in other shapes would need either multiple gravity generators to distribute the load across the structure, or to have gravity pointing in opposite directions in different sections of the ship.

Does the gravity field's shape or strength change when the generator is rotated or accelerated? This could provide some light comedy with people spilling their coffee at one end of the ship when it turns around, or it could be a serious limitation to how fast a ship can manoeuvre with the gravity generator on without tearing itself apart.