I think the difficulty here is you might be casting on with the wrong yarn?
I can’t be certain but did you have a yarn ball attached to your saved 22 stitches at back neck? And did you use this yarn ball to cast on with? This is what it sounds like to me but I may be wrong.
I would say you need to use a fresh ball of yarn (or break off from back neck leaving tail to weave in) and start your cast ons fresh and unattached to anything.
Cast on the 23
- if you used knit cast on they are on the left needle, now turn, making this the right needle with new cast on stitches and yarn at point end ready to work into the save neck stitches, work across these as per pattern with knits and makes.
- if you used thumb method or long tail method the Newcastle on stitches are already on the right needle with yarn at point end ready to work into the saved stitches. Work across these as per pattern.
After working the back neck stitches you need to cast on another 23 for the left side if the hood.
If you used the knit cast on method you will need to turn your work so that fabric and stitches are on left needle, then cast on 23, this puts the new 23 on the same needle as the worked stitches. Once you have done this you are already in position to work the next row, purl, right across the new 23, the neck 22 and the other side new 23.
If you used the thumb or long tail cast on then I can’t help, haha, sorry, I actually don’t know how they can be added at the end of the row. I think it’s not possible but may be wrong.
If it was me I’d add all the new stitches with the knit cast on method because I know how and they can definitely be added both ends.
The first lot of cast ons is the right hand side of the garment as you wear it, the garment is right side facing so you are looking at the back of it, the second lot are on the left hand side of the hood as you are wearing it.