I think I found out the key error:
60930 Nov 04, 2019 02:35:02.475 [15392] ERROR - Couldn't rename file "\\DISKSTATION\video\Serie TV\.grab\80bcc5c49664141f3627fb4f64a086b934dbde4d\Il delitto della porta accanto (2019) - S06E02 - Amori da incubo.ts" to "\\DISKSTATION\video\Serie TV\Il delitto della porta accanto (2019)\Season 06\Il delitto della porta accanto (2019) - S06E02 - Amori da incubo.ts": The process cannot access the file because it is being used by another process
52811 Nov 04, 2019 04:05:03.059 [14332] ERROR - Couldn't rename file "\\DISKSTATION\video\Serie TV\.grab\92601697275c9103a1de40fb5d2aef5232d72a09\Wolff - un poliziotto a Berlino (2019) - 1998-05-25 14 00 00 - Nel nome del padre.ts" to "\\DISKSTATION\video\Serie TV\Wolff - un poliziotto a Berlino (2019)\Season 1998\Wolff - un poliziotto a Berlino (2019) - 1998-05-25 14 00 00 - Nel nome del padre.ts": The process cannot access the file because it is being used by another process
70294 Nov 04, 2019 08:15:02.014 [8588] ERROR - Couldn't rename file "\\DISKSTATION\video\Serie TV\.grab\8ab61e3b0535ec3dc1818d20df151400a28e602d\Murder Comes to Town (2014) - S04E03 - Murder Comes to Town.ts" to "\\DISKSTATION\video\Serie TV\Murder Comes to Town (2014)\Season 04\Murder Comes to Town (2014) - S04E03 - Murder Comes to Town.ts": The process cannot access the file because it is being used by another process
The recording can’t be moved from the grab folder cause the file is in use, now the problem is finding out what’s using it, but I’ll find a way into it.
I found other topics discuss about that -> DVR fails to move file from grab folder to library on Windows
What bothers me, and makes me sceptical, is that not all the missing recording have a corresponding error line in the logs. I’m looking at the test C. (Wolff - un poliziotto a Berlino), the log speaks about the 2nd of 3 episodes, but not about the 1st and the 3rd. And later the test E. (Murder Comes to Town) is still successful even if the error line is present.
That logs inconsistency makes me think that the problem is not only the “cannot access the file” thing. I’ll try and clear that up first, and I’ll report back if I find something more.
