Premiere Pro 2020 won't slow down my 60 FPS drone footage correctly

I have the same issue with 120p footage.
I only shoot 120p (I modify to 24p)
I have troubleshooted for hours and have only came up with 1 solution. Use Premiere Pro 2019.
If you have creative cloud it should not be a problem to copy and paste everything from your projects into an earlier version.
This way you can avoid deleting your media cache every time you need to.

I have found a solution to mine but have also noticed a few things.

Even when I speed ramp, in the clip preview window, it's also dropping frames after I've speed ramped it or increased the speed of the clip.  

It will also then have that same skipping or reshuffling of clips in the sequence preview window.

BUT, when i clear my media cache and then adjust the size of the clip in the sequence (100% to 80% since I'm putting a 2.7k clip in a 1080x2160 sequence), re-render that section of the sequence, and then again delete all media cache, then the clip will play fine, speed ramped as desired.  

Again, for arguments sake, I'm speed ramping from 700% to a 47% from a 2.7k clip that was recorded at 60 fps and placing it on a 24 fps timeline.

Not really a workaround, but just a sequence of events that I had to do to get it to play properly.  Not sure if clearing out the media cache and then re-rendering that portion of the sequence is what's helping, but you can really notice a difference after I render that section of the sequence, then adjust size, then re-render that section again.

Lot of work so hope they get this fixed in the next update.  Has never been a problem for me in any previous versions of PPro CC.

Known issue. Use Thom's workaround. https://community.adobe.com/t5/premiere-pro/speeding-up-footage-results-in-lost-frames/m-p/10730675#M236600

Rather than slow the clip down, I think you need to right click on it in the bin, select modify/interpret footage, then in the frame rate box select "assume this rate" and enter 30fps