Can you try force quitting Avid Link (and the helper app) and see if the sluggihsness continues?

Still worked for me. The effect from the bin looks exactly as expected. Any chance someone could throw one of their effects into a bin, and ZIP the file to post?

Is still an AIFF-C media issue? Does it work if you use WAV media?

Hmmm... that is odd. In my example above (which wasn't clear) I was dragging it from the bin to the second clip, and it worked. Did you get a chance to try a new user?

I am not seeing that here, although I admit I am testing the next version, so I can't speak directly to 2018.12. I take a 3D Warp with start and end keyframes, drop it in a bin, then drag to another clip and both keyframes are in the effect. Anyone else on 2018.12 that sees this? @Fish, Can you also try a new Avid user?

This is a common issue with some MP4 files. Hopefully Avid will continue to improve its Generic Codec as we go forward.

Just curious...if you're placing an effect that was 10 seconds long on a 1 second clip, the ending keyframes will be well past the end of the clip, thereby not seeing much of an animation. Can you confirm that the end keyframes are past your clip by using the scroll wheel in the effect editor? I haven't checked this, but it could be a function

In the source browser, left-click the plugin next to the file and you should be able to switch it to QuickTime from a pulldown.

Try switching to the QuickTime Plugin.

I'm pretty sure this is in all versions of software, and not just Symphony... If you have an interlaced clip in a progrssive timeline, you'll see a temporal adapter on it. Select the clip and open the Motion Effect Editor. Promote the effect. In the main Motion Effect Editor window, change the Source to Interlaced (Output will default to your