Please help us help you and fill where relevant:
Your LimeSurvey version: 5.3.20
Own server or LimeSurvey hosting: Own Server
Survey theme/template: Black Pearl
==================
Hello,

I recently updated from version 3.27.34 to 5.3.20. Ever since then, the "Edit" question page is only showing the question in "Source" mode and i can no longer maximize the "question" field or view the question formatted.

Have these features been removed? Is my installation corrupted?

Thanks in advance,
Kareem
 

Change the editor type in your personal settings.

Thank you Joffm.

I changed it to "inline html editor" and it didn't work, I switched on debug mode and it worked fine, however, if i switch off debug mode, it stops working again.

Do i need to re-install?

You may clear the asset cache.
Though I never had to do this when I switched the type of editor.

Joffm
 

Perfect! Thank you. Clearing the assets cache solved it.