Ionic serve works, rollup error on build

Getting an odd error when trying to build to devices. Ionic serve works otherwise. Any pointers? Having trouble looking for this specific error.

[15:20:52]  ionic-app-scripts 0.0.23
[15:20:52]  build prod started ...
[15:20:52]  clean started ...
[15:20:52]  clean finished in 11 ms
[15:20:52]  copy started ...
[15:20:52]  ngc started ...
[15:20:52]  lint started ...
[15:20:52]  copy finished in 101 ms
[15:20:54]  lint finished in 1.85 s
[15:21:11]  ngc finished in 18.71 s
[15:21:11]  bundle prod started ...
[15:21:11]  Error: Could not resolve entry (./.tmp/app/main.dev.js)
    at {DIR}/node_modules/rollup/dist/rollup.js:8602:28

Edit: the actual problem is .tmp/app/main.dev.js isn’t generated, but I cannot figure out why.

Ok @ionic/app-scripts was out of date. No longer having problems after upgrading to v0.0.30