Weird load issue

When I load one of our solutions in Rider 2018.2 I get the following messages in the event log:

29/08/2018
15:05 Can't analyse webpack.config.js: coding assistance will ignore module resolution rules in this file.
Possible reasons: this file is not a valid webpack configuration file or its format is not currently supported by the IDE.
Error details: Cannot find module 'fork-ts-checker-webpack-plugin'

15:05 Project 'Maddison.External.Web' load finished with warnings: Error executing the AssignProjectConfiguration task. ' ' is an unexpected token. The expected token is ';'. Line 2, position 99. at (1491:5)

15:05 Project 'Maddison.Entities' load finished with warnings: Error executing the AssignProjectConfiguration task. ' ' is an unexpected token. The expected token is ';'. Line 2, position 99. at (1491:5)

This I assume is lead to the same issue of all basic types being unresolvable

Now the project still compiles and runs perfectly, just intellisense has gone badly wrong.

I've tried invalidating caches, deleting the .idea folder etc.

Other projects load ok, it's just this one that isn't

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Some extra information, if I load the projects individually they are fine.

If I create an empty solution and add the projects back in then the issue manifests itself again immediately