Ok, an odd one that I have not seen before.
NZBGet 21.0 (latest stable) on Win10, if important. no custom PP scripts loaded. only out of the box unrar/7za.exe present.
When downloading files, and it only seems that files with the suffix -4P in the name, which are on usenet as .7z.001, .7z.002 etc. so 7-zip archives that may have been renamed or hjsplit, the files download fine, and then PP kicks in. the file switches to 'renaming' and sits there indefinitely. it will not unpack the files until the next file finishes downloading, then it snaps into life and unpacks it while that next downloaded file sits in the same stuck state. I even tried pausing the entire queue (selected all items and paused rather than pausing globally) and when the only remaining file that is unpaused finishes downloading it just sits there. here is a screenshot after about 15 minutes of waiting with no change.
all that can be seen in the logs about this is the following (newest on top):
Fri Nov 15 2019 18:55:13 No renamed files found for Smallville.S09E01.Savior.1080p.BluRay.REMUX.VC-1.DD.5.1-EPSiLON-4P
info Fri Nov 15 2019 18:55:13 Loaded par2-file 6aa9f6df3e5547acb910f927f8189463.par2 for par-rename
info Fri Nov 15 2019 18:55:13 Checking renamed files for Smallville.S09E01.Savior.1080p.BluRay.REMUX.VC-1.DD.5.1-EPSiLON-4P
This is what it looked like when the previous file unpacked (when the above file completed downloading, again newest log on top)
info Fri Nov 15 2019 18:55:12 Deleting archive files
info Fri Nov 15 2019 18:55:12 7-Zip: Compressed: 6409005882
info Fri Nov 15 2019 18:55:12 7-Zip: Size: 6409005704
info Fri Nov 15 2019 18:55:12 7-Zip: Everything is Ok
info Fri Nov 15 2019 18:55:12 7-Zip: Blocks = 1
info Fri Nov 15 2019 18:55:12 7-Zip: Solid = -
info Fri Nov 15 2019 18:55:12 7-Zip: Method = Copy
info Fri Nov 15 2019 18:55:12 7-Zip: Headers Size = 178
info Fri Nov 15 2019 18:55:12 7-Zip: Physical Size = 6409005882
info Fri Nov 15 2019 18:55:12 7-Zip: Type = 7z
info Fri Nov 15 2019 18:55:12 7-Zip: Path = f0a9ea83c93d4a0b90ab018a05f14939.7z
info Fri Nov 15 2019 18:55:12 7-Zip: --
info Fri Nov 15 2019 18:55:12 7-Zip: Size = 6409005882
info Fri Nov 15 2019 18:55:12 7-Zip: Path = f0a9ea83c93d4a0b90ab018a05f14939.7z
info Fri Nov 15 2019 18:55:12 7-Zip: ----
info Fri Nov 15 2019 18:55:12 7-Zip: Total Physical Size = 6409005882
info Fri Nov 15 2019 18:55:12 7-Zip: Volumes = 61
info Fri Nov 15 2019 18:55:12 7-Zip: Physical Size = 105216000
info Fri Nov 15 2019 18:55:12 7-Zip: Type = Split
info Fri Nov 15 2019 18:55:12 7-Zip: Path = f0a9ea83c93d4a0b90ab018a05f14939.7z.001
info Fri Nov 15 2019 18:55:12 7-Zip: --
info Fri Nov 15 2019 18:54:44 7-Zip: Extracting archive: f0a9ea83c93d4a0b90ab018a05f14939.7z.001
info Fri Nov 15 2019 18:54:44 7-Zip: 1 file, 105216000 bytes (101 MiB)
info Fri Nov 15 2019 18:54:44 7-Zip: Scanning the drive for archives:
info Fri Nov 15 2019 18:54:44 7-Zip: 7-Zip (a) 19.00 (x64) : Copyright (c) 1999-2018 Igor Pavlov : 2019-02-21
info Fri Nov 15 2019 18:54:44 Executing 7-Zip
info Fri Nov 15 2019 18:54:44 Unpacking Smallville.S08E22.Doomsday.1080p.BluRay.REMUX.VC-1.DD.5.1-EPSiLON-4P
info Fri Nov 15 2019 18:54:43 No renamed archive files found for Smallville.S08E22.Doomsday.1080p.BluRay.REMUX.VC-1.DD.5.1-EPSiLON-4P
info Fri Nov 15 2019 18:54:43 Checking renamed archive files for Smallville.S08E22.Doomsday.1080p.BluRay.REMUX.VC-1.DD.5.1-EPSiLON-4P
info Fri Nov 15 2019 18:54:43 Queueing Smallville.S09E01.Savior.1080p.BluRay.REMUX.VC-1.DD.5.1-EPSiLON-4P for post-processing
info Fri Nov 15 2019 18:54:43 Collection Smallville.S09E01.Savior.1080p.BluRay.REMUX.VC-1.DD.5.1-EPSiLON-4P completely downloaded
any ideas? I think I have collated everything pertinent but if there is anything else let me know.