I don't know how you do it, but I can't recreate it -> the above bug always happens to me.
I am sending you a screen record of what it looks like when I go to save data in existing table or create a new table: hidden link
If by chance you cannot start the video, feel free to download it to your computer, and then start it.
The only time I can do the same thing as you in the video is when I disable the WPML String Translation plugin.
Ok, this is weird as I'm able to create a new table and save some data. Could you edit this table hidden link and add some data? Let me know how it goes.
Also, please try using another browser like safari and firefox.
I added data to your new table via 3 different browsers -> the results are always the same, I didn't manage to save the data and I got an error notice.
I am sending you a screenshot of all three attempts.
Ty for info, I was able to log in and test. I managed to save data in tables and create a new one. But again, I can't do the same thing with mine as well as with other accounts that are on the web.
It is very important for you that the shop manager who enters the data in the tables can do that, but at the moment he cannot.
So I think it is not a solution that only a new account can make these changes. If you want, I can add a plugin ((https://wordpress.org/plugins/user-switching/).) to switch the registered user so you can test it.
I installed the agreed plugin (User Switching) and activated it on the testing server. I also updated the wpml plugins, but I still have the same problem.
When I switch into your account via the plugin, I can normally edit a table or create a new one, otherwise I can't. Please test and let me know how and what to do next.
I was preparing a report but I cannot replicate the issue now on your staging site here hidden link . I switched to all the administrative accounts but I can edit the tables without issues.
Could you give it another try? If you're able to replicate this, please tell me which user you use and which table you edit.