Thank you for reaching out regarding the issue with the hover overlay effect on your gallery thumbnails. It sounds like this could be due to a conflict with your current theme or other plugins. Here are some steps you can take to resolve this issue:
Go to the general gallery settings located in the left side menu of your WordPress admin panel. Switch on the compatibility settings. This can often resolve conflicts and ensure that the overlay effect works consistently.
Temporarily disable other plugins to see if the hover overlay effect improves. If it does, re-enable the plugins one by one to identify which one is causing the conflict.
Try switching to a default WordPress theme (such as Twenty Twenty-One) temporarily to determine if your current theme is interfering with the hover overlay effect.
If these steps do not resolve the issue, please provide more details, and we will be happy to assist you further.
Thank you for your patience and cooperation. If you need additional assistance, feel free to reach out again.