Here’s how AxCrypt works:
1. When you open a file, it is decrypted to a temporary location, and then Excel is launched to open that temporary file.
2. When AxCrypt (which stays resident) detects that Excel is exited, it takes the temporary file and re-encrypts it back to the original location and then wipes the temporary decrypted file.
If AxCrypt crashes or is killed between 1. and 2. it can’t perform step 2, and while you’re saving the Excel file to the temporary location the encrypted original file won’t get updated.
However, the temporary file is still there, so if you notice this you can manually find it. With AxCrypt 2 it also detects that there’s an ‘orphan’ decrypted file, and you can click the clean ‘broom’ icon for example to get the decrypted file re-encrypted and update the encrypted file.