Hi Serdar,
I have experienced similar issues with the Rich Text Editor. This is a bug, and Mendix Support should take care of it.
You can create a support ticket here.
Best Regards,
Damir
Hi
Do you wan to check that it is empty or not for validation?
If so, try using this trim(replaceAll($RichText, '(<[^>]+>| |\\s)*', '')) = '' in decision.
Hope it helps.