Completely agree with the above comments. I did the same for my FK8 and ITS with the full acuity shifter assembly and shifter cable bushings.
If you're gonna upgrade your shifting, go all out even if you have to save up and do it later. It's well worth the money.
That happened to me before. Sometimes this works, not always. You can take your car to an empty interstate and just floor it from 10mph all the way to at least 70mph.
Sometimes that will dislodge whatever is stuck. Works sometimes not always.