This element uses delegatesFocus in its shadow root configuration, and has a div with tabindex 0 in the shadow root. Text cannot be selected when the selection begins on the inside of the element.
If you set display: none on the focusable div, select text, then show the div again, you will be able to select text as expected
It is always possible to select the text if you being the selection from outside of the element
Note: at the time of writing, this bug affects Chrome only (tested in stable 73.0.3683.103 and canary 75.0.3759.0 on MacOS 10.13.6)