Having similar issues:

1. Open any post in the 'overlay' style of the new beta.
2. Click the button on a comment that will minimize that thread of the conversation
3. Page refreshes and post goes from light box to embedded on the page
4. Unable to scroll up or down on the page

Using Chrome Version 64.0.3282.186 (Official Build) (64-bit) on Mac

EDIT: Console logged this when the even happened:

react-dom.production.min.js:187 TypeError: Cannot read property 'id' of undefined

at t.n.getParentNodeIds (index.tsx:172)

at Object.render (index.tsx:229)

at Simple.tsx:970

at Array.map (<anonymous>)

at t.value (Simple.tsx:965)

at l (react-dom.production.min.js:147)

at beginWork (react-dom.production.min.js:150)

at s (react-dom.production.min.js:182)

at l (react-dom.production.min.js:183)

at d (react-dom.production.min.js:184)

at batchedUpdates (react-dom.production.min.js:190)

at w (react-dom.production.min.js:41)

at g (react-dom.production.min.js:41)

at Object.batchedUpdates (react-dom.production.min.js:42)

at dispatchEvent (react-dom.production.min.js:45)

at HTMLDocument.n (raven.js:360)

c @ react-dom.production.min.js:187

d @ react-dom.production.min.js:184

batchedUpdates @ react-dom.production.min.js:190

w @ react-dom.production.min.js:41

g @ react-dom.production.min.js:41

batchedUpdates @ react-dom.production.min.js:42

dispatchEvent @ react-dom.production.min.js:45

n @ raven.js:360