Guys, thanks for your responses. I managed to get the attention of the Wyze Core Community group rep on FB, and she is going to forward it to the appropriate team.
It seems this is a long standing and ongoing problem with 256 Gig cards. The FB thread can be seen here:-
https://www.facebook.com/groups/298350110642283/?multi_permalinks=1330503370760280¬if_id=1648512747569031¬if_t=feedback_reaction_generic&ref=notif