non-tabbed rows (after the first one) cause the mindmap to disappear

[m8e]

If I add any non-tab-prefixed rows (after the first one) then the mindmap fully disappears, and JS console shows:

Uncaught TypeError: r.getClientRects is not a function at w.fn.init.offset (jquery.min.js:2) at Object.$.event.fix (jcanvas.js:2364)

Chrome Version 73.0.3683.103 (Official Build) (64-bit) Win 10 Pro

P.S. I think it could be good to have a few lines of instructions available in the menu, to explain the importance of TAB, and anything else that is not obvious (e.g. does the Calendar have any function or integration with the mindmap?)