This is not uncommon for Meraki where a product is slowly phased out where there is a better option available - or a similar option already within the Cisco portfolio.
A few examples are:
- No longer supporting USB 4G dongles with the release of the MG21 and MG41 products.
- Stopping development on SSL decryption on the MX with the integration of Cisco Umbrella which can do cloud based SSL decryption.
In this case, Anyconnect is a far superior product with better stability, features and functionality. Since it has MX integration (and has done for a little while now), the Meraki VPN is more-or-less being left behind in terms of its functionality.
If I were you, I'd begin looking at Anyconnect, or another VPN option rather than trying to stick with the Meraki native VPN.