Ring Video Doorbell wired (latest version) with Byron 776 Transformer/Chime Unit - no chime

Hi, along with many other UK based users I am using a Byron 776 combo chime/transformer unit to run my ring doorbell. I previously had a Ring V1 doorbell for a few years but it was beginning to fail so i decided to replace it with the latest 'wired' only model (https://www.amazon.co.uk/gp/product/B08LR3G17D/ref=ppx_yo_dt_b_search_asin_title?ie=UTF8&th=1). A simple swap out was done (new holes for the smaller unit mounting) and it is working fine from the Byron transformer. However the new bell does not seem to be ringing the internal ringer on the Byron unit. Someone elsewhere mentioned that there is apparently an option to enable/disable an external chime (i think this was for the ring 2 model from memory) however I can find no such option for the standard wired model. So now I can't work out if the internal chime has gone faulty somehow (although it powers the doorbell fine) or if will not support ringing the external chime. Has anyone else had similar issues with this combo? I am wondering if the fact the doorbell wired has no internal power source (which the old doorbell would have had) might be the problem... any advice appreciated. thanks Ads.