I had some issues too, now that I was doing my acrylic course. During black Friday I bought lots of tools and supplies, including a number of different glues to try.
I had (and trew away) an old Ebay glue that I mostly use for gems and stuff. I tried it once for tips because I had run out and it was horrible. Sticks almost immediately, literally like 1 sec! But it's too strong and almost had my fingers glued together! Stay away from it!
Ink London's glue sticks in 10 secs or less. I never had a problem. 0, nada it was perfect!
Lux nails' glue, which one of the other girls had at the school, was also very good surprisingly. Very similar to Ink's, good application, a bit stronger odour maybe, but definitely very good overall.
Pro impressions glue was quite a bit different. I picked it up accidentally, not noticing it wasn't Ink's and went on with application as usual and I couldn't get it to stay put. Too much pressure or too little would lift the tip. Too much glue, would never stick. Too little glue wasn't enough. Anyway, after lots of errors, I found out it's more gelish, it needs some secs to air-dry before you stick the tip on the nail. Love the tips hate the glue, can't just faff around waiting about it. Same goes with Young Nails' glue.
I have a CND's too but it's still unopened, so no idea how it performs. Gonna try IBD's too next. Perhaps it's just your glue. Don't give up on it.
And btw, I've heard that training hand needs a good buff before you stick the tip. Never really tried it myself though.