I2C1 doesn't work on V1.1

[chriskuku]

I bought an STM32F103C8T6 (WeAct Studio brand) via AliExpress last week. My program hangs in the I2C Initialization.

An OLED 64x128 Display is connected. With another BluePill (older unknown brand) the program works.

I bought 3 of them. Will try with the other two ones later.

Can I be sure that I bought from WeAct Studio? Is "WeAct Studio Choice Store" #the# trustable WeAct buying source on AliExpress?

EDIT: All 3 devices show the same effect: hanging up in I2C1 initialization. Adding 4.7K pullups to SDA and SCK don't help either.

[chriskuku]

Thinking about it I'll have to scrutinize a bit, e.g. whether F103 errata I2C related, depending on revision number matters. Will be back with my examinations.