A strange one this that perhaps has something to do with Javascript ‘strict mode’?
In this PG https://playground.babylonjs.com/#99XJ1H#4 lines 123 - 125 and 127 - 129 work with 136,137 and 144,145 when move button is clicked
In this PG https://playground.babylonjs.com/#KI8BJH#28 the corresponding lines 21-23, 25 -27 (called from lines 284, 289) produce the error
TypeError: setting getter-only property “visibility”
when Move Up button clicked
Using the code from PG #28 in a local file with the latest preview version of babylon.max.js the error is reported as on line 5733
Changing to an earlier version 4 of babylon.js ( 3 Dec 2018) there are no problems.
As you can see from this version of the PG https://playground.babylonjs.com/index.html#KI8BJH#30 lines 283 and 290 and this version https://playground.babylonjs.com/index.html#KI8BJH#31 lines 22,23 there is not a problem setting visibility directly outside the animation call.