Resolved! In the STM32MP157 I am trying to program an interrupt every 100 us using timer 14. It looks like the code generated is correct, but the result is not correct. It looks like the DiV4 has no effect. The timing is the same as no divide.
Looking at the clock in the MX Device Configuration Tool it says 204 to APB1 Timer Clocks (MHz).To get to 10000 Hz I have to divide 204 MHz by 20400. Fortunately there are a bunch of ways to do this. But on the first try I tried Prescaler 51Counter ...