I get asked the same question multiple times.
In some cases, it is resolved by request, and in others, it is resolved by itself.
I tested while disabling all but toolset, and tested by disabling all plugins and activating one by one.
Since the problem is occurring repeatedly, please solve this problem. And after that, please let me know how to fix it myself.
I use two hosting services. There are six sites in one place and two in the other.
Currently the problem is in one of two places.
I thought it was a cache problem, but it doesn't seem to be.
It's probably not a PHP related memory issue either. It's 1G level.
I've had this problem several times. There have been several occasions on other sites besides the current one.
It just happened a while ago, but it was resolved within the time it took to inquire and get an answer.
Thanks for the update; it's a good thing that the issue with the images has been fixed.
You're welcome to mark this ticket as resolved, but, in case it reappears, please start a new ticket, as soon as you can, so that we can troubleshoot it while it is still reproducible.
(also include the link to this ticket, for the background information)