i had this issue with burner #2 not lighting up after #1 (lefts to right)
if i turn up #1 then lower the flame, #2 lights fine. and the rest follow without issue.
probably just a bad tank, i got got one like this from home depot. something messed up with the threads on the tank valve so my hose never locked down enough to engage the oring. swap it out and youll be fine.
just received and order from thermoworks (paid regular price(mk4 thermapen and smoke), sent them off an email and they refunded me back the difference. great company.