Distributed computing strikes again; we've had to temporarily disable shared editing on VisualInk because under certain conditions the host (which included sessions with just one user, i.e. normal editing) could end up deleting some of their own work in a race condition. Ironically, updates from invited guests seemed to be always handled correctly.
We'll try and turn it back on soon, but data loss is one of those things we'd prefer to avoid even if it means disabling some functionality for a moment. Apologies if you were hoping to use the collaborative tools in the next few days 😞