Yes - it is because debug logging was disabled
It is possible that Plex Media Server thought you had the episodes already in the library - that can happen if episodes get matched to thetvdb and get changed from what is in the EPG. Earlier this year we stopped matching recordings to thetvdb and preserved the EPG data - that would avoid loss recordings or multiple recordings but if the show was previously matched to thetvdb then we would continue to that.
See EPG metadata is now retained for DVR recordings
To find the reason for the recordings to be missed - i would need debug server logs covering the time of the recording and at the end if it did start recording.
