Missing Scripts that are actually there after unity update

We have a large project (2019.2.6) file and want to add LWRP. I have made a new project using the LWRP template and intend to export packages from the original into the new one as LWRP will requie a Unity update, and we know from experience that this will cause errors.

So I start with an EMP grenade I have built that need LWRP for its electric visuals. There is a large list of dependencies but I export them all then import to the new project.

There are straight away missing scripts errors in the inspector, even thought these scripts are present in the new project.

‘The associated script could not be loaded’

The console says that the script does not derive from monobehavior but it does.

Can anyone tell me how to fix this please?

Also: I cannot save the project - it directs me to the console:

remove and reinstall textmeshpro