Hello Shaun, this is Martín, Tech Support Engineer from Teltonika Networks.
This is a known issue and it has been reported to RnD, and there is a workaround to fix it on 00.07.04.
Can you please go to Services>VPN>OpenVPN and hit "Save & Apply"? Or else, can you delete and re-create the VPN on VPN Hubs?
Please let me know if the issue persists.
Best regards.