Sweater sleeve increase?

Hope you can help me figure out where I’m going astray.

The pattern calls for 32 sts CO, then some 6 rounds K2P2 ribbing. From there, it’s STST (in the round) until 2" from beg (I assume from CO edge, not the beg of STST) then start inc.
"Increase every 8 rows 9 times until you have a total of 50 sts. "
I am having trouble figuring this out.
If every 8 rows I add one st, and do this 9 times, then I should only add 9 sts, which added to 32 CO gives me 41 sts, not 50. I am doing a M1, lifted bar knitting through the back loop style increase, as the pattern only states what is in quotation marks, and has nowhere at the beginning or end of the pattern stating which kind of increase is preferred.

What am I doing wrong? It is obvious at 7 times that this is not increasing enough, and the sleeve which was loose at the cuff is snug around the upper arm.
I did check the website for the pattern but can’t find it listed (free pattern came with handspun yarn). Gauge is accurate 3.5 spi/5 rpi.

After quoted part above it only talks about knit even in STST until piece measures 18" from beg.

Help? much appreciated…

You would inc at both the beginning and end of the row. So 9 inc rows = 18 sts increased.