I have a really strange bug found in Xcode's Interface Builder.
When I try to add an UILabel and UITextview inside a stackView using the Interface Builder, the stack view will be stretch with a width of infinite. For my UITextView I disabled the scroll and edit functions.
Before:
This is after I combine both elements inside a StackView:
When I use two UILabels and add those inside a StackView it's working correctly.