I realized a prototype including the STM32L433 (LQFP64 package). I tried to use the pins PH0 and PH1 as OUTPUT pins. This should be possible according to the datasheet (5V tolerant I/O pins). This pins can be used to attach a crystal or oscillator to the controller. This external clock would act as HSE, which I do not use (haven't installed). So disabled the HSE as well as the LSE.
I wasn't able to set the pins PH0 and PH1 HIGH. Interestingly, for the pins PC14 and PC15, which are responsible for the LSE, it works fine. I defined the pins PH0, PH1, PC14 and PC15 in as push-pull outputs.
Is it possible to use PH0 & PH1 as GPIO pins, or have I missed something in the datasheet?