Was there any change in the OS, admin privileges, API version and operating environment?
Also, for testing purpose, can we get access to repositories that you are using? Tools Network and another working repo?
This happens on 5 different systems with an EXE calling the VIPM API--no changes were made to the code or OSes besides regular Windows Updates. As for access to the repository, you should have access to the LabVIEW Tools Network repository as we publish it to the NI FTP here: ftp://ftp.ni.com/evaluation/labview/lvtn/vipm/index.vipr
This is the repository we're having trouble with when using the API and it is quite large.
Here is the internal repo I tested with and did not have any trouble adding a package to using the API (no changes were made to code outside of changing the repository name string for the API call):