Can't add tuning parts

[RudolfHucker]

I've been playing for 162 hours and had no issues replacing standard parts for tuned parts but now it won't let me do it. Tuned engine parts or exhaust parts are in my inventory but when I try to place the part I get a message saying that I don't have it. This doesn't happen with standard parts.

Any ideas as to what's going on?

[Mardoin69]

Did you add mods to the game? Like, for example, the QoL mod or TK Aftermarket...? If so, be sure MelonLoader is set to use version 0.5.7.xxx and not a newer version. May even need to uninstall mods, verify files for CMS2021, and start over installing the mods.