MXAO trouble

I don't know why there are some places of my game where the shadows from the MXAO suddenly disappear and reappear, and there are reverberation problems. I do not understand, this is recent and does not come from the few last updates of my GPU. I try a lot of things but I don't know how to fix that shit....Could you help me please....? Thanks a lot

On...

Then off...

Re-On...

Then re-off...