Heeey! Sounds similar to when I pop plugs out of the pockets in my dome's tray. My cloning success rate is still abysmal though...tried almost every popular method (even bubble cloner) with varied success rates. Zero consistency!
Will give this a shot and see what happens.
Also, are you feeding the mom normal veg nutes? I've heard success rates increase when plants have more P. Kinda noticed this as well when I switched nute composition.
I feed 6/9 in veg with Coco. There are certain clones that may need to be trimmed. I am trying a few clones right now that are defoliated except the top growth. We shall see how they do, they are really big clones. Also took a couple smaller, still huge, clones and did not trim. First time cloning this strain, so we shall see.
Cloning in Coco is really easy, but I will admit, it took me a few attempts to get it down perfect everytime... Once you get it, it works better than any way I have tried....which is a TON!