[Windows defrag does not see C: drive after I used Defraggler on it]

1. Windows 10

2. Defraggler free downloaded from CCleaner.com

3. It started off at 10% fragmentation, I noticed that C drive is missing from the system defragmenter while it's running.  I Stopped the defrag when it was down to 1% fragmentation (reckoning it's good enough and wanting to see if that brings C back into the list on the system defragmenter) but C remains missing there.  I've tried rebooting and also clicking into defragment from C drive's context menu.

4. Yes, I can still use defraggler on C

Thank you in advance

[Windows defrag does not see C: drive after I used Defraggler on it]

No, I explicitly did not tick that option when installing.  I can launch the default windows defragmenter just fine--it just doesn't show the C: drive as an option.

[Windows defrag does not see C: drive after I used Defraggler on it]

Hmm... any idea why this may be happening?  C drive is my system drive, is a spinning rust drive, etc.