iOS app crashes when references (parallel passages) are tapped

The script of this app is non-Roman and the problem is with some references (\r marker). They occur as parallel passage links in the gospels, for example. They used to work in an older version of the app, built with a previous version of SAB (in 2019). They still work when I export the book collection to HTML in a browser. But in the iOS app, the app immediately crashes when such a link is tapped. I tested this in Simulator and on a physical device through TestFlight. Could someone have a look at this please?

I have sent a private message to @Friedo about this.