thats strange.Unles the EAF is moving the focus when you go to that tab?|?!!??? I have never experienced that behaviour myself tho. Maybe disable the EAF(pull usb out) assuming the current focus position is good enough that you can see stars in the capture module.
And then take some images with the same exposure length in the focus module.If the camera driver works in one module then usually you should have no problem in any of the others.
Your using the same exposures length right/?
On the rare occasions i hav had something weird go on with ekos I have also tried to replicate it on another device.. i.e try it from my laptop or another rasbery pi.
I have two pis one with stellarmare and one with astroberry etc.