Chrome proxies hang with open idle connection

Using Chrome 75.0.3770.142 on Windows, with addon 0.0.7 and the latest static page at https://snowflake.torproject.org/snowflake that was committed 2019-07-27. Started Chrome, enabled addon, and opened 3 tabs with the static page. The addon and all 3 tabs all established good client connections within an hour or two, exchanged data both directions for a while, and then stalled out with the client connection staying open, preventing serving any other clients.

All 4 client connections have been stuck in this state for 2 days now, with the addon just showing 1 connected and 0 in the past 24 hours, never changing, and the 3 tabs all just repeating "websocket --> WebRTC data: 543 bytes" every couple minutes with no transfer size change or any data flowing in the other direction. The 3 tabs show connections to clients at different IP addresses, so I don't think it's just a user leaving their client window open forever.

A similar test on Firefox with the same deployment date shows more expected behavior of a few clients served each day per tab or addon, with connections being closed after transferring data for a while and then later serving another client (so the dropped broker connection bug seems fixed there).