Node debug not following path mappings to vagrant since 2018.2 update

Since updating PHPStorm to 2018.2, my vagrant-hosted Node.js breakpoints now will spawn a new read-only tab when hit rather than going to the point in the local file. Breakpoints are still hit, but I can't set them in the read-only tab. If I "copy path" on the read-only tab it gives me the path to the file inside the vagrant vm. My PHP breakpoints were unaffected by this.

So, despite there being a path mapping in the Node debug config to point my local dir to the VM dir, breakpoints still spawn these new tabs. My path mapping was there before the update and worked perfectly, so did the update introduce / change some setting to cause this?