Hi Jayme Edwards,
Welcome to the MSDN forum.
Refer to your description, I tried to reproduce this issue on my local and I found most of those packages cannot be downloaded and install, only little packages work fine, please have a look at the following:

I have reported this issue to the VS project Team, please check the following screenshot, then we need to waiting for the feedback from the VS product team engineers, sorry for this inconvenience and thank you for your understanding.

Best regards,
Sara
MSDN Community Support
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