I had a weird thing happen with my Delta 2 Max (first) on Sunday. I took it outside for solar charging (as usual), hooked it up and all was going along fine. It had started around 35% and after a couple of hours was up to 74%. Then, next time I looked on the app, it was still at 74%, and showed no input from the solar panels.

I did the following, with no results:
1) Unplugged, and replugged the wiring to the pigtails and checked the connections to the panels
2) Removed the pigtails and plugged the panels in directly.
3) Brought a D3+ over and checked the panels. This affirmed that there were no issues with the panels or cable extensions - the D3+ showed charging as expected.
4) Turned the D2M off, and plugged the panels directly in. This woke the station up, and it showed charging for about 2 seconds, then the charge stopped.
5) Checked my settings to make sure the upper limit didn't somehow get changed, it showed 100%
6) Checked the FW version, which was up to date
7) Checked the battery temp (it was a little over 90* air temp), the battery showed 90* which is well within specs.

No faults were showing and I got tired of messing with it, so I brought it inside and let it sit. Yesterday morning I used the station to make my coffee, breakfast and run the dishwasher. Later, I took it outside for solar charging, and it started charging fine. It eventually charged to 100% (happy dance). I'm not sure what the issue was, but letting it sit overnight seemed to solve it. Maybe it was really full on Sunday, but the BMS was confused. IDK, never had anything like that happen before.