Stuck door - you were right!
Okay, after much work on this door and trying to get it free, a mobile repair guy came by with a tool that helped extract the broken latch out of the door. Even though the latch was free enough to move and appear to not be broken, it was broken internally.
Ted (& Melinda!) - of course you were correct and the latch was indeed the issue. I've ordered the replacement latch kit from the link you provided - thanks so much for your help!
Have a great week!
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