Fusion render problem

Hi

Having problems with Fusion after the upgrade to the beta (both versions).

When I open a project begun in v18 with a Fusion graphic on a video track (featuring text on a white rectangle and animated lines powered by a Midi file to create a EQ visualisation) everything works fine. But if I make a small edit to one of the Fusion node's text, the Fusion layer disappears and a red horizontal line appears over the video itself (NOT over the timeline - ie it's not an indication that the Fusion graphic still needs to render - it doesn't fix itself even after the timeline line turns from red to blue).

NB once the Fusion clip render has disappeared there's no way to bring it back, even using Ctrl-Z. But since I've duplicated the timeline for a backup, I still have a working version of the graphic - albeit one I can't edit.

Moreover, going into the Fusion page itself, I then experience odd behaviour, incl no window visualising the graphic I'm working on.

I'm wondering if this might be caused by a corrupt cache file? If I copy and paste the Fusion elements into another video, they do render.

But there's also odd behaviour in other pages too - ie if I make a Fusion-only layer it displays as Media Offline in the Edit page. I'm not sure if that's related.

Any advice gratefully received - I'd assumed this was a v19 bug but I don't see others reporting it.

NB Editing on a Mac Studio M1 with 32GB of RAM.

I solved this - and hope the following is useful to anyone having the same issue:

1. Select the composition and use the 'Open in Fusion' command

2. Go to the first Mediain node

3. In the Inspector's tools panel, change Media Source from 'Timeline' to 'Background'

(I also deleted the Render Cache under the Playback menu, but I don't think you need this step)

This fixed the issue and the Fusion composition rendered and appeared as it was previously.

Not sure why, but the 19 update seems to have changed the relevant setting, meaning your composition will be blank until you do this.