I've been migrating Trello cards, testing first on phab-01. The cards I created from February 19 onwards aren't viewable by others, e.g. https://phab-01.wmflabs.org/T697
The card history has:
> Maniphest changed the visibility of this Task from "Public (No Login Required)" to "**Custom Policy**". Via Old World · Thu, Mar 5, 7:25 AM
> Maniphest changed the edit policy of this Task from "All Users" to "**Custom Policy**".
(Chasemp wasn't sure what **Via Old World** means.) Back in January Maniphest on phab-01 didn't reach in and change card settings, e.g. https://phab-01.wmflabs.org/T488
I can reproduce by filling in the form at https://phab-01.wmflabs.org/conduit/method/maniphest.createtask/ . I suspect the fix is to explicitly set viewPolicy and editPolicy in the conduit request to some undocumented value, but phabricator.wikimedia.org doesn't need this step. Or maybe my import user "[[ https://phab-01.wmflabs.org/p/trellimport/ | trellimport ]]" needs different settings.
The workaround is to edit each task and change its "Visible To" and "Editable By" fields; sadly I can't do this in Maniphest query's batch editing mode.
(This isn't high severity or priority for my work.)