Extraneous validation error message
 

One of the characters in a portfolio is a Ranger. That character is getting a validation error that says, "Deadeye's Arrow: This is a 1st-level spell, but you can only cast up to 0-level Ranger spells."

She doesn't have that spell, and after going over the character with a fine-tooth comb I can't for the life of me think of why HL thinks she does.

No tabs are red, and no red text appears anywhere in the character screens. It's only in the validation box and in the status bar.

How can I start finding the source of the problem?

In this forum, find the stickied thread named General Hero Lab Support & Community Resources, and in that thread, find the link to the bug reporting form. That's the correct place to report bugs like this. When you get the automated reply to your bug report, reply to that and attach a copy of this character, so that we can take a look at it, and figure out what's going wrong.

And welcome to the forums