Cannot edit ui-codemirror in a taskpane of an add-in in Excel for Windows

[SoftTimur]

I just realise that we cannot modify texts in code-mirror in a taskpane of an add-in in Excel for Windows.

I have an Excel add-in built by mean-stack and angular-ui-router. In a page, I have

<textarea ng-model='testCM1' ui-codemirror='option'></textarea>
<ui-codemirror ng-model='testCM2' ui-codemirror-opts='option'></ui-codemirror>
<div ng-model='testCM3' ui-codemirror='option'></div>
<textarea ng-model='testTextarea'></textarea>

The 4 textareas can well be edited in Chrome, IE, Excel Online, Excel for Mac. However, all the 3 textareas by ui-codemirror can not be edited in Excel for Windows, whereas the last textarea is modifiable.

Is anyone aware of this odd behavior? How could we fix this? Is there any workaround?

PS: here is a JSBin for testing, we could link this file to a manifest and try it in Excel for Windows.