I started to get some 'No ignition' errors on my Independence, which indicates that no temperature rise was detected upon ignitor and gas being turned on. I could hear the ignitor clicking away as well as the gas solenoid clicking on, so that left the propane path. Upon investigation, I found some residue on the inlet port of the regulator (see yellow circle below):
I don't have a picture of the actual regulator and residue, this is just a picture to show where it was. I cleaned the residue out with a toothpick but it would still occasionally have an error. Then this morning, I found it with the error again, and no amount of retries would get it to ignite. Upon googling how to clean gas regulators, apparently you just dunk the whole thing in a detergent solution. So, with nothing to loose, that's what I did. Basically soaked the whole regulator in a detergent solution for a bit, with lots of agitation, and then rinsed it out with clean water, several times.
I then connected it back up to the tank and tried it out again. It still failed to ignite for the first few times, but after that, it started to work again, and I've tried it now periodically over a period of 6 hours now and it has continued to work correctly.
Time will tell if this is the actual problem and solution. It COULD still be an internal issue with the solenoid mechanism, but I was too lazy to disassemble the unit at this time, so I'm hoping this is the problem. I also found this
replacement regulator that should screw into the existing fittings, but at about $50, I will have to eliminate the solenoid before resorting to buying a replacement regulator.