Thank you for contacting us.
I spent some time investigating your issue and it turns out that this is very annoying bug that we have missed. I logged it as a PITS issue
and you can vote for it and track its progress. However the names of the fields turned out to be important factor for reproducing this issue. If I name my image field "image2" when creating the module and then when I edit the fields I add an image field named "image1" and save it everything works as expected. But if I create a module with an image field "image1" and then I edit it to add a field "image2" I get the same mess as you.
What I am curious about are the error messages you get when you delete images, libraries, content items and so on because I didn't get any warnings or errors. If you can provide more information about the error messages it will help us a lot to localize the problem and fix it.
For now I am suggesting that you plan carefully what your module is going to look like and minimize the changes with fields editor because we are experiencing problems with it and we are doing our best to improve it for Sitefinity 5.0. Also build your module in a clean project and when you are sure what your module is going to look like recreate it in production environment.
I apologize for any inconvenience this is causing.
the Telerik team
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