Page Forms can't save tables defined by pipes (|), so instead using pipe comment ( {{!}} ).
When field is VEditor, the content parsed by parsoid which returns tables with pipes.
So you can't resave table.
Steps to Reproduce:
Change 555469 had a related patch set uploaded (by Anysite; owner: Anysite):
[mediawiki/extensions/VEForAll@master] Fix collision collision between PageForms, VEForAll and parsoid - pipes in tables.
Change 596852 had a related patch set uploaded (by Anysite; owner: Anysite):
[mediawiki/extensions/PageForms@master] Fix collision between PageForms, VEForAll and parsoid - pipes in tables
Clarification: the suggested patch have two parts: one in VEForAll and one in PageForms, this parts working together.