AxCrypt app will encrypt most of the file types. Also some file types AxCrypt will not encrypt due to security reasons.
AxCrypt will not encrypt any system files, temp file, hidden files and operating system installed drives/folder. So please avoid securing that kind of folders.
If you are receiving the warning dialog frequently, please click the Don’t show this again option. After that you never see this kind of warning.
Still, you are facing any issue, please provide detailed information about the issue and write a mail to firstname.lastname@example.org. We are happy to help you.