Suggest then as this is still randomly happening for you, as you have a paid eM Client version from your other threads, to login to the VIP Support page and lodge a support ticket to be investigated.
They can then advise what logs etc to send in to determine the cause of the issue.
I’ve retested it again this morning on Win 11 23H2 and I still cannot replicate that with the same eM Client V10.1.4588, so I don’t believe it’s a bug and suspect some other factor causing it.
However if there is other users on this forum experiencing the same issue, they will no doubt update this thread.
The only problem I have found with the Hover over attachment “which I created a thread for previously” is on the Mac where that “after the attachment loads in the preview window” (it’s blank) and you have to then “move your mouse away and then hover back” to see the preview.