Actually no, the Innovv K2 app has been pretty reliable. It's been a lot better at getting and staying connected than the companion app for my Viofo A129 system.
I think I found the root of my problem. Seems the SD card I was using, a Samsung Pro Endurance 128GB, has died. I did't have any problems with it before or during installation, but I guess it started dying some time during my hour-or-so test ride yesterday.
I tried connecting to the K2 over WiFi out on the road, but got the "camera initialization failed" etc. message shown above.
Tried WiFi again once I got home, same problem.
I shut the system down and removed the SD card. I would have to put the card in a PC to get large quantities of video off of it anyway, hence why I installed the DVR on Velcro inside the fairing originally (it's far more accessible!).
The card kinda worked in my PC, exactly once. It didn't want to work in one card reader, then it was accessible in another, then it didn't work in a third. Then it stopped being recognized at all, I mean as if the card wasn't there at all. My phone thought the card needed to be formatted.
I tried all the usual things (restarting PC several times, different cards, different readers). The card was just plain dead.
The K2 didn't behave right as long as that card was inserted. I either got the warning shown above, or else a generic "SD card error!" message. I tried formatting the card while it was inside the DVR, but the DVR just rebooted. Last time I tried it, the K2 thought there was no card inserted - as I said, card seems to be totally dead now.
As soon as I switched to an older, 32 GB Transcend SD card, the K2 started working again, including the app. Going for another test ride later. 32 GB isn't much capacity, but will do the job while I get a warranty replacement for the 128 GB card.
Guess I had bad luck with the Samsung card. I've been using the same model card in my A129 system for a couple of months with no issues.