We recently discovered some potential issues that could cause some long-term problems with how we create and export Parts from the Codeblocks workspace. To protect user's Designs, we have locked some Codeblocks Parts until we can fix the issues.
Because of these 'locked' parts some design may display a 'Node fails to load' error. This happens when the locked part refuses to load into the workspace.
Since this is primarily limited to Parts created in the Codeblocks workspace, this should only affect a small number of your designs. This issue will not impact any of the Parts created in the 3D workspace and even some older Codeblocks Parts will remain usable. This issue primarily effects Codeblocks Parts made in the last 6 months or so.
Once we have made the improvements, we will unlock the Codeblocks parts and the Designs should return to normal function. We're working to fix this as soon as possible.
In the meantime, if you need to use the Codeblocks-based Parts, you can create new Parts by exporting from your original Codeblocks designs. These newly-exported Parts will function as expected.
If you would like to remove the 'Node fails to load' error, you can Copy all the parts in the Design and Paste them into another Design (in a second browser tab). This will Copy and move only the items in the scene, so the 'locked' part will not be selected or pasted into the new design.
We're working hard to fix the issues and get these Parts unlocked and Designs fixed as soon as possible.
We're sorry for any confusion or inconvenience.
The Tinkercad Team