Moving this to Support for now until we can find steps to repro on other sites. If it’s reproducible here or on try.discourse.org then it can be treated as a Contribute > Bug. I’ve tried to browse the topic in question on your site from my mobile, and couldn’t repro the blank page at all.
First question is always: does it work in safe mode? RedwoodJS Community
If yes then it’s likely to be a site customization - although if this were true I would have expected to have seen it also.