Ultrastudio Mini monitor AND Fcpx 10.4.3 y High Sierra

Hy for all, since I updated my Imac 2013 to osx High Sierra and fcpx to vo. 10.4.3 my video output through ultrastudio minimonitor with thunderbolt 1, is a problem. The playing is slow down, go to jump sometimes. Look like to my imac or graphic card havent force. This issue appear by SDI to monitor sony, or by HDMI sony TV. My project is a 1080 25p, from downscale 4K 50p. This kind of project were reproduced without issues before the update. The BM Firm is the last in suport. To comment also that when I disable the output video from FCPX, I can do play and move very well in the timeline. anybody have this problem? Thanks.