Thanks for testing it and for the feedback.
So you've got the exact same software and different hardware and you think it's a software problem?
It's not completely impossible for that to be true actually, but it's far from likely.
Do they all work on older versions? You are using a different cap from me, and for the small LDO boards you're not using a diode, something I've never tested myself and it depends on the LDO quality as you've seen. Is this an LDO build? Does it have a diode?
It's possible that you're right on the edge with your hardware, and some work and some don't. Watchdog clocks have a little variation. Capacitors have a little variation (20% actually for yours), etc. My hardware has TONS of room to spare, but if your hardware is marginal, then this can happen.
Have you ever gone through the exercise of determining how much extra cap time you have? Voltage measurements are one way, but the most reliable is to use the OTSM-debug config option and compile.I probably should document that better, not that anyone will likely read it. Then on every click press it will flash out the number of sleeps that occurred. For long presses you'll either get the number or a 255(or maybe nothing instead of 255). No blinking at all or 255, means it lost power. A number (in quarter seconds) means it was still going. So you can see what the longest click possible is.
Did you try them with an earlier version? Even if the answer is yes and they worked, it doesn't change the possibility of things being right on the edge, but it gets more interesting. I have tested timing on 3 boards with >1.5 builds and they all work. 2 of those were OTSM and one was e-switch, which never runs out of power. Anyway, let me know if and which earlier version worked.
If you're using different hardware though, you really should go through the exercise of running that test.I haven't invoked that config option in awhile, so let me know if it's not working. There's a chance the debug blink-out got moved to early with some changes.
All this said, there is a known bug (that I'm zooming in on slowly I hope) that causes very occasional instability, that was introduced somewhere recently I think, I'm guessing maybe between 1.4.1 and 1.5, but, although it does present strangely, never anything remotely like what you're describing. Still if 1.3-r2 works for you, great. (I may re-post it soon).
I'll take note though and keep an eye out for poor timing performance.