Collar-Trouble (Dancefloor Tank Pattern WATG)

This is my first time knitting a vest and i cant seem to get the collar right. The pattern is the Dancefloor Tank from Wool and The Gang. I am having trouble with the 4th step... It says to "Slip the first stitch knit-wise" and then knit the rest of the round in a 1x1 rib pattern. I have to repeat this step 5 times. The problem is... that the 1st stitch keeps twisting and the collar keeps getting longer. I have tried to keep knitting but the first stitch gets so twisted, that it is almost impossible to keep slipping it knit-wise. I dont know what i am doing wrong... I have started over 2 times, and eventually left it for longer than a year... I picked it up again a couple of days ago, hoping that the long pause would have magically helped, but i still dont get it. Also i cant seem to find anything similar that i can look up to understand how to knit this... Has anyone done this pattern or something similar and knows how it is done? I am grateful for any help i can get!

https://preview.redd.it/n5hzga1awwqe1.png?width=581&format=png&auto=webp&s=c94652e9837a9aa8192633407a99ca469077728c

https://preview.redd.it/oadpdv1yvwqe1.jpg?width=1536&format=pjpg&auto=webp&s=766c6bf9b568ce2dacb943fec1f7867253c3e8c2