Welcome! I’m sorry I didn’t respond to your questions. Your initial problem, the inability to transmit from one radio to another a foot away could have been explained as simply as desense, but it could also have been different tones or even different channels or some combination of the three. Or configuration issues. Such as when your transmit light didn’t come on when depressing PTT. That might have been on a frequency where transmissions were inhibited. Anyway, good job figuring things out; that’s the spirit that will truly teach you the most.
Again, welcome!