Attached, as requested

Cheers!

Your survey behaves as expected for me. Working editors in questions MR06 to MR10.

I don't know how you can say "as soon as I hit the 'Previous' button to see what happened, it reverted to HTML" when there is only one group in your survey.

You're right: the test file created from the main file seems to work perfectly.  As they are exactly the same, it seems so weird that this extract works fine but the original causes problems.

BTW, I thought you only wanted a sample, so I deleted all the other sections and just kept one section for you to test.  If you're interested, I can copy/export again but keep 2 sections, so you can test the 'Previous' function?

I'll go through and change the code in all the question groups and retest.  If it's still not working, I'll report back.  Thanks for your ongoing help. You're so kind.

I suspect that some JavaScript unrelated to the TinyMCE editor is throwing an error. Check the console (F12) for errors.