Hello @saad_rashad,
Thank you so much for sharing.
Of course, to escalate this back to the developers, we need to check for existing conflicts with more than one plugin.
Would that be possible?
– Temporarily deactivate all your plugins except NextGen Gallery.
– Is the problem solved? Then, it was caused by one of your plugins. Please check one by one and find the one causing the problem.
– If the problem is not solved with the deactivation of the plugins, try changing to a standard WordPress theme, it could be a conflict with your current theme.
If you are 100% sure that our plugin is the one causing the conflict, we′d like to take a closer look. If so, please send us a bug report here: https://www.imagely.com/report-bug, refer back to this forum thread and let them know Gaby referred you.
Possible workaround
A solution based on other forum thread, they mentioned that disabling zlib.output.compression in PHP config should fix the problem.
Nevertheless, we would like to report this back.
It will be great to have some feedback.
We do appreciate these reports from the WordPress community.