I had the same issue (version 1.5.23), no correct redirect after confirming the reservation since a short while. I found out that in Chrome and Edge (latest versions) the redirection-url containing the /?ahbnocache= is not handled correctly and the user is confronted with an empty page. In Firefox whoever it works correct.
Only if I change the url for the redirect to another domain than where AHB is running Chrome and Edge handle it correctly. From there I redirect back to the original reservationpage.
This workaround is not a problem, we use AHB just for two rooms with a very small group of colleagues.
