What else should ‘Read Only’ mean? One must have applied the setting and should have known what he (f/m) does.
If needs arise to cancel protection: There are different containers of text that can be protected (tables by every singel cell; frames - just to name two examples). Thus a refined design of using protection in a document / template is possible. A global switching off of protections will not be available.
I think the documents should be analised with the help of the navigator to identify the containers concerned - and, of course, the templates should be reworked to get documents as intended.
Editing: In a comment above “jerquee” linked in a thread from another forum on LibreOffice. There “jonhayes” had attached an example file to his post. Having studied that a bit with the help of an XML-editor I think the most likely cause of the problem is carelessly pasting content copied from non-odf source and containing incompatible or unsufficiently specified field-types. For better understanding you may refer to “owengs”'s contributions to this thread. The bug in LibreOffice should be to not refuse accepting pasted contents that cannot be thoroughly validated for one or another reason. We experience just another aspect of the “compatibility dilemma” enjoyed to the full by an unfortunately powerful competitor.