Hello together,
I've just installed Node Red on Docker (using WSL). Unfortunately, the objects disappear after I drop them into the workspace.
They are literally there, I can identify them in the info section. Also, I can export the flow and import it to another Red-Node application. It must be my node red application.
Problems like this will be related to the browser rather than runtime/docker etc.
What browser are you using (including version)? There is a known issue with Safari 15.3 that looks similar to this. We know that is fixed with the latest Safari 15.5.
If you're using a different type of browser, please share the details - and please also check the browser's javascript console for any error messages.