I2C SCL pin no clock output

[SSin]

Dear all,

Sorry for this old questions ( & and seems not fixed).

I use STM32CubeMX w/ vs code to build a program in STM32F103RE. And the I2C master seems not working. It always raise AF error. Maybe this is due the salve device problem. But once I probe the SCL pin with my DSO, nothing is found! And once I try to run the code step by step via debugger, the program will sometime freezed due to busy flag!

I googled it and find there are many bug reports on this topic. But none of the solution can solve the problem. Can anyone please give me any tips?

Attached please find my project

[SSin]

Sorry, my fault. Change the external pull up from 2K to 1K is okay now. But any reference can be provided to explain this?