Hubitat lost Konnected boards, now can't discover

Well, this is odd. Hubitat used to talk to Konnected boards fine until I did a 2.2.6 firmware on them. Then, two boards (of four) stopped reporting state. I tried a bunch of stuff to back out the boards that stopped responding, including deleting their Service Manager instance, re-flashing the board, re-flashing and erasing the board, using the java monitor tool to listen to the board while doing Hubitat stuff, no joy.

So, I pull the entire Konnected app and children out of Hubitat to start fresh (reboot) and now I get this at first board discovery:

java.lang.StringIndexOutOfBoundsException: String index out of range: -2 on line 150 (pageDiscovery)

 All components are Konnected v2.2.6. Hubitat is v2.0.8.latest. Not sure where to go from here.

After a lot of rebooting, the Konnected app is discovering again and I have the boards attached. I'll leave this here though so the error is recorded.