As I posted on Reddit, there seems to be issues with NDB tuning on some airbases. I haven't done a detailed examination of this, but there is an obvious test case - Kobuleti.
I have a few theories about what is causing this as I have managed to fix it on my install.
Basically, I couldn't get a signal from Kobuleti. I made a new mission, put an Mi-8 and Mi-24P into it, flew near the airport and couldn't get either of the two NDBs.
I would imagine most of my old missions I made had this problem (I'm not going to test 40).
I've now fixed my DCS and new missions work correctly when tuning to these frequencies. To fix my DCS, I deleted a bunch of DCS files and ran an integrity check via Steam.
I deleted and redownloaded all the following (from DCSWorld\Mods\terrains):
So it's fixed! - No. It's not. If I join multiplayer servers, many of them have the same issue. The old missions I made also have this problem and there doesn't seem to be a way to fix it.
I've attached two mission files that demonstrate a broken and a working version of this.
Test - NDB Helos and Helos 2. Helos has the broken NDB and Helos 2 has a fixed version. I hope this helps you recreate the problem. Please let me know if there's anything else I can do to help with this.
I think it's an issue with old installs of the game. I installed my copy of DCS World February 2014. I think Steam failed to update some of the necessary files or I may have edited file and they weren't fixed with new updates to the game. It may be a Steam only issue.
I'm definitely not the only person this affects as I've had other players in multiplayer servers confirm this is an issue (having them fail to tune to Kobuleti but able to tune to other local stations).
Is there any way to fix my old missions? I don't want to have to recreate them.
TEST - NDB Helos - v0point004.miz TEST - NDB Helos 2 - v0point001.miz