As there is no bug section for the complete range of applications, I post this bug / reminder here.
And for sure this is a bug. If you offer a feature which is not working - not in retail, not in beta - means you have to fix it (soon) or offer it, when it is solid working.
My problem with tiled printing is, that you have no clue, where to combine? the printouts, as there are no tile marks. Additionally the printouts are not name like tile 1 of 6 or similar. Attached an image from ID as it should be for tiled printing.
Right now I use a large printer, but a while ago printing a dummy A0 on A4 using Affinity would have ended in a disaster (or more extra work).