I'm pretty sure that in #18 it was revealed he'd been frantically looking for her but to no luck.
Well the X-Factor #116 and the Sabretooth:Back To Nature oneshot were set in between Volume's 1 & 2.It was also shown in a One-Shot during his stint in X-Factor that Wildchild was still in touch with Alpha Flight. Though I couldn't blame Alpha for loosing track of him nearly as much as the members of X-Factor at that point. Hey guys, Sabretooth is at large again, the Hound program is at work, and Wildchild who had been slowly changing for quite a few issues now, has gone AWOL. Shouldn't you be concerned?
After Volume 2 started AF had their hands full with their own issues, plus new members, distrust and Dept. H to deal with.
By the time we get to X-Factor #142 that's roughly between #9 & 10 of Volume 2.
We know she came to Dept. H looking for a fight with him because he rejoined the team pre-Volume 2 #1.We know Diamond Lil was looking for Jeffries at least, why weren't any other Alphans or anyone from the training groups with her?
And she was kidnapped by Dept. H before any of AF had a chance to see her and realise he was missing, let alone send people to look for Madison with her.
Plus they'd been mind-wiped to forget Madison was ever there.
Personally I hate it when writers give too much technobabble and ruin the sense of story and fun. Each to their own.I can't stand it when writers use that as a cop out without any technobable as to how it's being done.