I am having similar issues with, what I believe to be, an IDAS system.
It isn't in the RR DB yet but this is the FCC info on it:
ULS License - Industrial/Business Pool, Trunked License - WQLM715 - Arconic Inc. - Frequencies Summary
This isn't a very active system at all so I started by scanning all 10 frequencies conventionally and was hearing mostly NXDN motorboating with occasional voice decoding while seeing TG, UID, and AREA info with IDS as the indicator (occasionally I also saw NX4) . I was only hearing activity on 2 of the frequencies and at least one of them had a data burst every 5 seconds or so.
Then, I put all 10 frequencies into a NXDN trunk system (using IDAS TG format) and ran the LCN finder for several hours. It never even found 1 channel (it stayed at 0/10 the whole time) even though there was definitely traffic during the time frame (I was conventionally scanning with my other 436 at the same time). Just for giggles, I turned off the LCN finder and put the scanner in ID Search mode just to see if there was activity but I got absolutely nothing. I then changed the TGs over to NXDN TGs with no change.
Then, I read the claims about setting the channels as FM and Manual 8 threshold so I retested with those settings and noticed there was a noticeable improvement with NXDN decode (way less motorboating) and increased signal strength while scanning conventionally.
Lastly, I made the same changes on the trunked system (FM, Manual 8) and restarted the LCN finder. Unfortunately, nothing changed... the LCN finder ran for about 2 hours with no change (there was definitely activity during the time frame) and absolute silence when ID searching the system. I also changed from IDAS TGs to NXDN TGs and back again with no change.
I know the next step would be to submit logs... I am familiar with the process and would gladly do so, I just need to know what I should log?
Log while?
Scanning conventionally
ID Searching the trunked system
running LCN Finder on the trunked system
various combinations of the above with both NFM and FM settings
All of the above