Thank you!
Ok. You are right. The issue must be related to something deeper. I just copied the part in the model which raised the issue, but now all operations on x seem to have same issue.
Had to investigate this in more detail…
Is it possible to dump all relevant information of a tensor to better reproduce issues like that?

x: torch.Size([8, 8, 89]) torch.float32 cuda:0
s: torch.Size([8, 8, 89]) torch.float32 cuda:0