I recently tried to use windows desktop app version of lightroom. I used version 5.3 of the lightroom and I was first unable to add the photos and most options are greyed out. I first thought this was a permission or licensing issue so (I am using enterprise) I logged out and logged back in and uninstall and reinstall. They didn't fix the issues. Since other application premier photoshops all working fine, I have ruled out license. The apps are installed on extra internal sata drive different from my OS (all my adobe products are).
The other thing I noticed from preference and the syncing to cloud storage is stuck with calculating... The webversion lightroom works fine.
Doesn't sound like you got a clear response. I did a chat with support and they are saying that LR is no longer supported and that I would need to subscribe to LrC. I rebooted several times and couldn't find a work around at all. I'm sifting through post now and doesn't look like anyone can answer anything clearly.