I see that you’ve obviously previously set the Track 8 to be a Flex assigned to RecBuffer 8 and then changed it to a master in order to have access to the buffer in the editor as it’s otherwise not possible to get the waveform up
however, I suspect the issue is that there’s (sort of) no machine on the track to play the audio back, or more likely this usage scenario wasn’t catered for - it’s a quirk for sure, it’s actually quite handy that the record track on Master 8 still works, so I agree it’s a pity that the buffer doesn’t play (for whatever reason) - it may be worth flagging this up, but I suspect it may be supposed to act the way a neighbour track does when you pre-arm with its respective buffer and have a recorder active, in this case the editor waveform simply displays n/a
something’s a little inconsistent somewhere for sure
You might not even need to load the buffer to a flex as samples can be previewed from the sample slot list, just try to preview from the flex list on any flex track by having the buffer selected (rectangle around it) without even loading it (pressing enter while selected).