This is an annoying (and bizarre) property of the Bubble text element… (if contiguous text is too long to fit in a Text element Bubble just ignores it completely, as if it doesn’t exist, and leaves the text element empty.)
Unfortunately there is no native workaround for this (that I know of).
So whenever I need to truncate Contigous text (such as a long URL), which to be honest is fairly often (this is not an unusual requirement), I just ditch Bubble’s Text element completely and use custom HTML to do it.
That way you can have full control over how it displays.
So that would be my suggestion here.