Although there is no debug info, it seems that Nextcloud returns an error when DAVx5 requests the events/contacts. Is there any indication that this could be a DAVx5 problem?
I sync Android with Owncloud and have found that the 'Organization Field is not syncd in either direction.
Is this possible to correct?
I installed on a second device and it worked with Organisation on that - so I uninstalled from the first device and when I re-installed it worked there too.