Record hidden when tree view selected

Hi,
I’ve deployed v1.9.3 on docker accessing Mysql and set up a tree collection called folder (!)
It has standard parent child setup.
I have a workflow that can move a child to another parent. The data in the database all looks right, but for some reason the child does not show then the tree view option is selected, but does show when the “tree table” option is removed.
I do a refresh with the button and a hard refresh with the browser, but it does not show under it’s parent. If I move the record to have no parent, it shows again.
Any ideas? Is this a bug or is something else going on?
Thanks

There is a table named “main_xxxx_path” in the database, and the data in the table also needs to be processed.