Hi @Anonymous User @David_Brooks
Thanks both for your comments.
Problem solved! (well partially) Having realised that the map was visible on the Survey123 website (in the record details on the right hand side), it got me thinking.
Basically, I uninstalled and reinstalled the Survey123 app on my mobile device and hey presto!😁
However, on the app, the map will not zoom in to the required scale. I have labels set up in the webmap for a specific zoom level and the basemap etc is visible within the webmap when I am zoomed in to view the labels, but in the app I cannot zoom in enough for the labels to appear.
Thanks again for your comments.
@David_Brooks Unfortunately FieldMaps does not provide some of the functionality we require from S123 (report generation, MS Flow webhooks etc) so for the time being we are sticking with S123. (I am aware I could have used Fieldmaps for the geoshape question, but for the moment we are using S123)