UART Disabled output in certain functions

Hello,

I am have been using hal.uartD with a ftdi to send data to external computer for year or two. I did all my uart calls in userCode which has worked with success over different apm builds. Recently we have been working with a new vehicle type which needs a little bit of debugging. I added hal.uartD->printf’s in stabliize_run() to see what commands were happening(I added some additional code to stabilize) but I found that the printf’s don’t execute unless I put them in the UserCode functions. This behavior I found to be odd and was wondering if someone could clue me in.

thanks

currently using Copter 3.3-rc5 for reference