Hello @NTMan, the attached minidump matches your previous recent issue reports, and this is another symptom of #5489. It's probably best to add a comment on that issue report with the other symptoms that have been collected.
Additionally, radeonsi_dri.so is in the backtrace, so it's possible this is a regression involving mesa, but it's unclear at this point and we'll need to hear from a Steam dev.
Closing as a duplicate of #5489.
Nothing extracted yet.
Your system information
Please describe your issue in as much detail as possible:
Demonstration: https://youtu.be/t5ydCZhRGq8
/tmp/dumps/crash_20180525212937_1.dmp
steam backtrace