Where are your originals stored? If you cannot edit when you try to go into details mode unless you have made smart previews you will not be able to edit. If you make smart previews upon import and the location is an external hard drive and that drive is not connected you should still be able to edit in Develop... not clear on the problem.
Please post your System Information as Lightroom Classic (LrC) reports it. In LrC click on Help, then System Info, then Copy. Paste that information into a reply. Please present all information from first line down to and including Plug-in Info. Info after Plug-in info can be cut as that is just so much dead space to us non-Techs.