I started with two polymer Rivals last year. I tried running my usual reloads, which were 147gr, flat nose, coated rounds, but I had the same problem of rounds getting stuck in the chamber and having to really crank on it to get the slide back. Rounds were loaded to 1.145 OAL. The same thing happened when I tried truncated nose, FMJs.
I had both barrels reamed by my gunsmith for $40 total and never had a problem again.
As others have said, the guns made in Europe are made for 124gr NATO round nose loaded pretty short. I know a lot of people with CZs and Tanfos who have had to have their barrels reamed.
Oddly, at the beginning of the year, I replaced my polymer Darkside with a chrome Rival-S. I haven't had to have it reamed. Not sure why, but it's probably because I started running 124gr round nose FMJs or plated that are loaded shorter (1.125 OAL). The specs are much closer to what you find in a factory round, obviously with less charge.