Hello, friend!
I experimented with the operations you described on the U2000, but I didn't encounter the situation you described.
I doubt whether the problem is caused by the U2000 version. Currently, some earlier U2000 versions have stopped providing services, and some functions of the U2000 may be faulty.
You are advised to check the U2000 version. If the version is too old, contact the service provider to upgrade the version.
Thanks!