hi kyle and welcome , i guess you are using a ts 55 , how good and what blade are you using for this as 18mm ply is not that awkward to cut even at that angle , also how far are you lowering the blade into your angle of cut , sounds like you are getting a bind some where i would look at your blade first of all then the saw , does it bog down at say 45 degree cuts , i have the 55 r & 75 saws and have not suffered anything like that , try a panther blade if you do a lot of ply , also are you supporting your work piece i know it may sound obvious but you would be supprised how many people do not , make sure your guide rail doesn't move ( clamp it if it does ) how far along the rip does it stop ? let me know i am sure you will get the answer on the forum.