When I go to a Flow-enabled Talk page I see the loading cursor (cursor: wait;) indefinately and the overlay never goes away (flow-ui-load-overlay). If I go into my browser's inspector I can set flow-ui-load-overlay to hidden and continue to use Flow.
I should point out that even hacking around to 'use' flow shows that it doesn't appear to be talking to Parsoid. I don't see the mini-VE editor at all.
I'm running the master of both MW and Flow. VisualEditor is working as intended. Parsoid is parsing pages. Memcache is memcaching.
My Flow config is as follows:
$wgFlowOccupyNamespaces = array( NS_TALK, NS_USER_TALK );
$wgFlowContentFormat = 'html';
$wgFlowEditorList = array( 'visualeditor', 'none' );
$wgFlowParsoidURL = 'http://localhost:8000';
$wgFlowParsoidPrefix = 'mercywiki';
$wgFlowCacheVersion = '8.7';
$wgDefaultUserOptions['echo-subscriptions-web-flow-discussion'] = true;
$wgDefaultUserOptions['echo-subscriptions-email-flow-discussion'] = true;