After 1.8 version upgrade Version details not showing for our Custom Theme and also showing duplicate theme showing with same name,
Generally for private theme there is no versioning maintained. Only for marketplace theme versioning is maintained. In your case JioMart theme is private theme thats why it is not showing version.
Astra theme is marketplace theme so version is showing for this theme.
You can refer to this doc : Create a Theme | Fynd Partners Help Center