Scan for channels getting different results

Any reason why 2 HDHomeRun Primes with cable cards I’ve had for years would have different numbers of channels being found? Is this a cable card issue I should contact Fios about?

Anyone ever run into this? It hasn’t been an issue for recording and it’s difficult to tell what’s missing but I don’t want to run into an issue where I can’t record something because the free tuner can’t see that channel?

Not unusual at all. Check the Silicon Dust forum HDHomeRun Hardware Setup & Troubleshooting - Silicondust.
My HDHR Prime randomly (when it does its background scans every 3 days) decides I'm not subscribed to channels that I am.
It's highly annoying, but Silicon Dust doesn't seem to care.
I used to capture the channels every week (using http://ip.address.of.hdhr/lineup.xml?show=all) to compare what changed, but finally gave up after realizing SD wasn't listening.
Now when I'm missing a channel I subscribe to, I just do a manual channel scan.

You're not alone. I had 3 primes, and they all had different channel counts, fed from the same input.

SiliconDust thinks they're infallible, and you're unlikely to get any response from them.

Thanks. I figured I’d get a better quality answer here than on SD or sitting on support with Verizon for an issue that might not be their problem. This is indeed frustrating but at least I know it’s a known thing.