This will be fixed with the next update, coming the next few days.
Viewing post in [RPG Maker] WYSIWYG UI Editor - Battle (Pro) comments
Cool that's good to hear, it actually seems like the font size is not working. I adjusted the window size to better fit what I want the UI to do now and suddenly the item text appeared. I found that specific window sizes I got item text (although very small font).
Idk if this helps but it's good to hear it's being fixed soon! Thank you so much for the support!