[Jason Brown] “Is this cause for major concern as 601 is an SD color space?”
Within an intelligent decoder like the Media Composer application, the simple answer is no.
If you attempt to play back 601 within a 709 environment that assumes all input will be 709, then, yes it would be a problem, mostly because the RGB –>Y’ matrix coefficients are different. But Media Composer, knowing you are operating in 709, will (or should) flag the 601 media as requiring a different matrix extraction, and unify the media, exactly as if you were bringing legacy footage into a fresh edit timeline.
Why your Alexa footage somehow got flagged as 601 is the bigger mystery.
jPo
“I always pass on free advice — its never of any use to me” Oscar Wilde.