Hi keren,
Hmm in a quick test on my end, pressing F7 to launch spellcheck is working on Windows. To confirm, are you seeing that the spellcheck dialog isn’t popping up at all, or that it’s not detecting the text that you want to check (if the latter, then is it widget text or text in other areas of the UI such as widget names that you’re checking)? Does the dialog pop up if you go to “Edit > Spellcheck” instead of using the keyboard shortcut?
To confirm, are you currently on the latest build of the beta? If you’re not currently on build 3642, then please update to see if that fixes it since we released some fixes to resolve issues with popup dialogs.