Gradle dependencies not found in IDEA

I recently updated a java 8 project to use jdk 11, gradle from 4.6 to 5.0.

The command line build works fine, however the IDEA error checker does not find classes from the gradle dependencies (ex: javax, spring framework classes).

I've tried re-importing the project, deleting the .idea folder and regenerating it, using the latest IDEA version but, nothing worked. 

Managed to reproduce it in a spring boot application I've created just for this. Any ideas?