Pretty sure the last docker update wiped out any user specified java mx setting. That could be your issue, @Boyturtle if you made that change in the Crashplan console.
Where I was hitting a loop where block synchronization would restart after about 30%, I'm almost at 80% now with no issues after setting the mx value again. Thanks all for the help.
@jademonkee Let us know how it goes. I just ran the java mx command and set it to 8192 as that's what I have set in the container settings. Currently at 17% sync. I've got 28TB in the cloud backup.. so this could take a bit.
@Shonky I'm having the same issue. Thank you for sharing your workaround! I'll give that a shot. I did do a little searching and did find this - https://wiki.archlinux.org/index.php/CrashPlan#Restore_stuck_preparing, but I'm not sure if it applies here.