Eight seconds is too long an exposure to expect the drone to be able to manage.
Even at two seconds, I would shoot several times to have a better chance of having one good one to use.
But what does that mean?
When you move the GPS receiver 5 metres, do the coordinates show that?
Or do they stay the same because the repeater is just rebroadcasting the coordinates for the location of the static repeater?
Unfortunately, while it will provide GPS, the GPS reading will not change while the drone flies around inside. It's ideal for functional testing indoors, but not useful for flying a drone around indoors, while navigating the space...