Vinyl liner bead falling out

Hey everyone,

Since my husband and I bought a house in June that has a pool, I have been mostly lurking here. I don't have much to contribute right now, being a newbie, so I would really appreciate your input here!

About a month ago I purchased and installed a bead wedge to put on top of the liner. The old bead wedge was falling out, cracked and dry/brittle. The liner wasn't falling out but I didn't want to let it get that far. The stuff I bought was like this one, but not as deep (it's more like a wedge than a protrusion perpendicular to the bead): https://www.amazon.com/Beaded-Ground-Pool-Liner-Lock/dp/B002ZJ3LD2

I installed it with the help of the butt of a butter knife to really push it in. It didn't "click" as I read in someone's comments on another thread about bead, but it went in and seemed to be snug. One corner popped out once during a swim but we just put it back in with no issues again.

Fast forward to this morning. About half the pool had no bead, it had fallen into the pool!! I installed it all in one piece so I guess something popped out and the inertia just kept it going. I am so glad it stopped and wasn't the whole pool.

I am wondering why this happened and what I can do to avoid it. Is it possible the liner shrunk due to the overnight temperatures? The pool was 64F this morning. It was 66F yesterday morning. It's getting colder and colder overnight here.

Should we just close the pool? Will this same thing happen over the winter though if the liner shrinks some more?

Thanks in advance for your advice!!