You really are a great help
I commented out the shutter high line in the mirror lockup sequence. It now behaves exactly as I expected
Of course I have no intention of actually using mirror lockup. I do not believe it is useful in this type of photography.
I shall be using the MLU pin to control an external lamp. I also intend to utilize another two or three pins for extra flashes and I have noted in another post how to do this.
I look forward to your next release with individual flash delays.
Keep up the good work