Printing from iPad Pro

I have been using AirPrint between my new iPad Pro and a Canon Pixma MG5350 without difficulty - until over the past week. For some reason it seems to print a single page OK but if I want to print a succesion of pages, it prints really small which I can’t possibly read! When this happens the paper is taken from the back cassette, usually used just for photos, rather than use the front cassette. I have looked at the printer's settings and everything looks OK. I can’t understand why this has all of a sudden - I haven’t changed anything that I can think of.

Any my advice would be welcome. Many thanks.