I have noticed this in the last few days but my spell checker while in IE does not seem to be working. Quick search and I found the following solution
- Navigate to edge://settings/languages
- Remove extra languages (Potentially Optional)
- Swap from “Microsoft Editor” to “Basic” for the Writing Assistance > Grammar and Spellcheck Assistant
I tried it and it did work. Not for sure if its a certain build of Edge or OS or a little bit of both, just wanted to share. Have a great day.