This release fixes #1653 (PR #1656). MobX 6.1.0 introduced a new issue and this addresses that. Thanks to @urugator!
There should be no breaking changes.
This new approach, replacing makeObservable with manually created actions and computed views, also seems to have improved instance instantiation speed (MyModel.create()) by about 20% in @jamonholmgren's benchmarks.
Please report any new bugs and we will address as soon as possible. We wanted to get this fix into the hands of users ASAP as previously doing yarn add mobx mobx-state-tree means you would end up with brokenness.