I have this occasional problem whereby:
On our Adobe Managed System, (not Cloud), on the crx/packmgr UI, I click on the upload package.
However, the file picker menu doesn't allow me to select a local file to upload.
Eventually after some time retrying, sometimes hours, it will eventually work.
I am in the administrators group.
What do you mean by the file picker menu doesn't allow me to select a local file to upload - Is the system hanged during that time? If yes, could you please verify the CPU usage during the issue. It might be due to high CPU usage on your system.