Can no longer create text boxes, only shapes

I make the slides for my church service every week using the online version of PowerPoint. I've just attempted to make the slides for this week, only to find that it's no longer possible to make text boxes.

Selecting the 'Text Box' option will make a shape instead. Right-clicking to add text will instead create an entirely new shape, in which each line of text will overlap. Using ctrl+shift+V to paste results in each line of text being inserted with an extra space in between.

I've looked at the list of recent updates, and none of them mention changing or getting rid of text boxes.

Hoping someone can help, as I need to get this working again urgently in order to create slides for the service.