I also use the CY8C4246AZI-M443 chip, I can assign two uart and one I2C, the same pins as your description.
Do you mean you update the project from creator V3.2 to V 4.2 directly, and meet this issues?
1) In PSoC Creator 18.104.22.1681, please go to Tools -> Find new devices and install device pack.
2) Restart PSoC Creator and let us know if it helps.
Tanks for your answer,
yes, you're right. The error occured after updating PSoC Creator Version V3.2 to 4.2
Which is the version you are using?
You can attached your test project in this forum, I can test it for you.
I try to configure two uart and one I2C in creator, everything is OK.
You need to try to allocate the three component in SCB,SCB and SCB.