If you can see a VST library in Library Manager and you have an active license on e-licenser but can’t load it, this worked for me with Groove Agent 5 and Songwriter Essentials expansion pack (just one VST library was missing - all others had installed without the need for this disabling of the firewall - I had tried everything else I could find on the internet). I ran into this issue after a fresh install on a new PC.
\
- Uninstall VST library from Steinberg Library Manager
- Uninstall VST library from PC using Add/Remove Programs
- Disable all firewall/virus protection
- DL/Unzip/Install library in default folder
- Re-enable firewall/virus protection
Of course also get all the updates and let e-licenser do what it does.
The VST library Songwriter Essentials consists of two files, but only one was showing up (and in a directory different from the others). Firewall was blocking one of the files even when I moved it manually, etc.