I have a project where I need to output a precise waveform to drive some external FETs and thought this would be a good opportunity to fill a DMA buffer with CCR values and tie this to TIM2 that is configured with output capture on channel 1. Just for testing, I have the cnt period setup for 1 microsecond, but this will get changed to 1 nanosecond, I have this setup on a NUCLEO-H745ZI-Q where the user push button starts the DMA. When I start the DMA, I am getting a short pulse where after the falling edge of that pulse, the output delays for the full timer period (ARR set to 60), then I get my waveform (which in this example is 3 short pulses). I am doing all of this on the M7 core. Here is a github link to the main file and the entire source, config, etc. I attached a photo of the output from my scope. You can see there is a single pulse, followed by ~60 microseconds, and then the waveform I wanted to generate.
