Try the new version of the GPU plotter that @cryo just posted a couple days ago (v4.1.1) in the thread that I made about the issue:
https://forums.burst-team.us/post/76558
I also had similar issues with Direct mode that it would just sit there at ~0.25% for quite a long time (apparently writing all 0s to the plot file, instead of instantly creating a dummy file like CPU plotting does)... So, all the time it is hung there, it's literally doing nothing but writing 0's to a dummy file before it even starts the plotting process of generating nonces. The new version (v4.1.1) should address that issue, and worked MUCH better for me.
