I've been working pretty heavily in timeline in 2019.1.5 with custom tracks (generated using the Timeline Playables Wizard tool). I finally updated to 2019.3.4 last night and it appears that all of my timelines are broken, none of my old track types are recognized and can not be built on new tracks. They simply say "Track cannot be loaded" and do not appear in the drop down menu of track types I can create. I am not getting any errors related to timeline. Did the structure of how timeline tracks work drastically change?