I assume this problem has affected the Web GUI since basically forever, or at least I myself have always had this issue when operating it. Basically, if you do multiple modifications quickly where each of them is supposed to save changes to the config, some of them will likely be lost, especially when dealing with slow hardware or slow connections (e.g. when operating the GUI remotely).

To reproduce (on slow hardware or a remote connection):

1. Edit multiple folders quickly one after another (e.g. by changing their folder type to something else).
2. Wait for the GUI to become responsive again.
3. It is very likely that only some of the folders will have their type changed.
4. The rest of the modifications have been lost and need to be re-done.

I think a solution to this could be to simply force the GUI not to accept any input before actually saving the previous modifications to the config. One method to achieve this may be to show a "saving changes" pop-up or similar so that the user would know that something is happening while also being prevented from operating the GUI. Of course, this method isn't flawless as it's possible to have the same GUI open in multiple browser tabs and try to make changes from there, etc. but still I believe that it would be much better than the current state where modifications can be lost very easily.

I may try to do something about this problem myself, but of course, if someone more skilled is willing to do work in this direction, it would be very welcome too.

Issues related to this problem: #8589 (and possibly others, I will add them here if I find any)