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.
Since this is primarily limited to Parts created in the Codeblocks workspace, this should only affect a small number of your total Part Collection. 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 Parts and they should return to normal function.
In the meantime, if you need to use the Parts, you can create new Parts by exporting from your original Codeblocks designs. These newly-exported Parts will function as expected.
We're working hard to fix the issue and get these Parts back to normal as soon as possible.
We're sorry for any confusion or inconvenience.
The Tinkercad Team