Changing the speed of a video is broken in several ways.

[mhwarner]

I added a single clip.  Changed the speed to 200%.  It changed the stated video duration but it did not speed up the clip.  Also, I could not publish the show to an .mp4.  The publish window just sat there and never did anything.  It did create a 1KB file with the name but that's all.  I went back in and tried to change the speed from 200% back to 100%.  Moved the slider then manually typed in the number.  Closed the window and PTEAV just locked up and I had to "End Process".  

I started over with another clip.  I changed the speed to 50%.  That worked ok but then I tried to trim the end of the video and the window never showed me the end.  I could go in and trim the video first and then set the speed to 50% and that worked fine.  

Just for the record, I experiment with ticking the "Interpolation" box for this video, but the video then became quite blurry.  Apparently the interpolation is only intended for extremely slow videos.

I tried again with the second clip and trimmed in first then set to 200% speed.  Duration changed, but not speed.  Went back and again attempted to reset speed to 100% and the little display window went black and then when I closed the Trim and Adjust Speed window, PTEAV once again locked up and I had to shut it down.

I tried one more time and trimmed first and adjusted speed to 200%.  Duration changed, actual video speed did not.  This one did publish.

Setting video speed definitely has some issues.  Let me know if you need further information.

I did go into V11 and set the speed on both videos I had tried to 200% speed and they did indeed speed up and I was able to save them.

FYI, I am on a PC running Win 24H2 with 64 GB memory.