I’m putting this out here right now, as I just spend two hours banging my head against a wall, becoming more and more convinced that witchcraft was afoot.
If you are using boostrap tabs, and have a set displaying generally correctly, but with just one or two that won’t open no matter what you try then I may have the answer for you:
If your target pane ID begins with a digit then it WILL NOT WORK.
Whack on a prefix and all will come right. Good lord that was frustrating!