
Are you using OnCalculateMinMax ?
You may have a situation in which for a brief instance one of the plots included in the scale either has no value (IsValid = false) yet its default value is out of scale, or has an out-of-scale value e.g. zero. You might think that if the value isn’t valid it wouldn’t be included in the scale, but there are certain parts of the system where that does not appear to be always being checked first.
You’re probably right. I find posts in the old forum describing the same thing.