After working with fusion I have saved my project. When I try to re-open that project I can't see any nodes in Fusion tab. There is only MediaIn1 and MediaOut1 nodes. Below yo can see the screenshot. How I can see my nodes again? OS: MacOSX Big Sur, Davinci Resolve Version 17 Public Beta.
It depends on how you created the Fusion compositions in the first place.
If your Fusion clip exists on your edit timeline, then when you're in the Fusion tab, you'll see it listed if you activate the "Clips" panel (at the top of the screen, or under Workspace->Show Panel in Workspace->Clips)
If your Fusion clip doesn't exist on your edit timeline (there are a few ways to do this), then to find it within the Fusion page, you'll need to navigate to it through Fusion's "Media Pool" tab. Resolve's Media Pool contains all of the elements you've imported or created within the context of the currently open project. If you don't see your Fusion Clip there at first, don't panic. To see absolutely everything in your project, first you need to expose the sidebar of the media pool, then select the "Master" bin and all children of it by shift-clicking the last item in the list of bins. With all of the bins selected, Resolve shows all of the available content in your project. Your Fusion composition should be listed there.
The reason you're not seeing the nodes you expect to see in the screenshot above is that whenever you switch to the Fusion Page from the Edit page, Resolve turns whichever clip that currently intersects the Edit timeline playhead into a Fusion clip, and populates the node tree with a MediaIn and MediaOut node. If you don't make any alterations before returning to the Edit page, Resolve will turn the Fusion clip back into a normal clip (at least, in recent versions of Resolve).
To put it another way, the moment in time you're viewing on the Edit page will be the same one you're viewing when you switch to the Fusion page, complete with any Fusion nodes you've set up previously (if any), or set up for a new composition if you haven't created any yet; the Edit timeline playhead and Fusion timeline playhead are linked.
In Fusion, the "Clips" tab lets you skip from one clip to the next down your edit timeline, and the playbar only scrubs through the length of one clip. But since all of your Fusion compositions don't necessarily need to be on your Edit timeline, the Media Pool holds all available source material.