No, not the Minoc issue that is discussed quite regularly.

I'm further through the storyline, trying to get help from Trellek, but when I go to his wife and she refuses to let him join, there is no option to explain the reason I need him. I've had my fortune read and gone through the normal steps, yet this appears to stop the storyline dead.

Could it be because my party decided to attack a Wisp instead of a pack of Wolves? Or could something else be at work here?

She should say that you need Salamon's permission. Once you get that, you can tell her that you got it. After she asks why you want him to join, tell her wisps.

I've done that, but when I go back to her the specific option to mention wisps doesnt appear. The only options I get are "adventure" and "never mind". To make matters worse, Saralek then no longer even has the option to talk about giving permission, and Salamon insists on once again seeing the signed contract, even though I already gave her it once.

You need to talk to Taylor of Empath Abbey about wisps. He sometimes hangs out near the moongate. You skipped that part of the plot.

did that along the way. Like I said, I did the normal steps in the quest

Talking to Taylor about wisps sets gflags[0x0138] to true which adds "wisp" to the choices of "adventure" and "never mind".

So I should add that this is resolved. It turns out that although I had spoken to Taylor, I had clearly done so in a thread of gameplay that I didn't go on to save. Backing up a bit fixed things and the quest is progressing as it should.