Ionic-cache

Is Ionic-Cache removed in V4? I get the following error after installation:

ERROR in node_modules/ionic-cache/dist/cache.service.d.ts(1,10): error TS2305: Module ‘"<>/node_modules/rxjs/Observable"’ has no exported member ‘Observable’.
node_modules/rxjs/Observable.d.ts(1,15): error TS2307: Cannot find module ‘rxjs-compat/Observable’.

looking like it is using the old version of rxjs