I remember watching an English language (probably live-action) film as a kid (on the TV, but I don't think it was a series) about which I remember the part where there was a group of people who could turn invisible when they held their breath and, at one point, they are almost given away while hiding when one (possibly a child) can't hold thier breath long enough. They were possibly aliens. This would have been early 80s, I think, but possibly an older movie being reshown. What movie was it?
Based on the holding-one's-breath-to-turn-invisible plot device, the time-period, and the match of many other descriptions you gave, I'm guessing this is the film you are looking for.
In the comments for this video, someone posted
"Thank you for uploading this. I must have seen it when it aired on NBC in '82, because I remember the "holding your breath to turn invisible" thing, and particularly the scene shown briefly at 3:04. It's been bugging me for decades, wondering what this movie was. Now I know. :D"