Three first steps to make sure:
1, Are the Theme, all the Theme's Addon's and Wordpress up to date?
2, Do you have any Custom CSS, HTML or JS that when temporarily removed allows you to see the Image-hover button
3, Do you have any third-party plugins installed that when temporarily de-activated allows you to see the button?
If the imagehover addon "Set Hover Image" button does not show up, please make sure the imagehover addon is installed in the folder "wp-content" / "plugins" / "laytheme-imagehover"
you can look at the folder by accessing your webserver via FTP.
if the folder name is different, the button will not show up.
However this issue has appeared with not just you,
And is likely a bug that we need to fix
Others with this issue also seem to be having trouble updating in general
If able please try the advice given from @arminunruh in these threads
& let me know how you go so we can fix this bug!
Thank you for your patience and for using Lay Theme