After some more testing in my home network, with a Cisco 1841 and a RUTX08, I believe that I found the reason why the Cisco stayed master when the Teltonika has a higher priority: the VRRP daemon on the Teltonika uses an advertisement interval of 2 seconds by default, and my Cisco uses 1 second by default. This can be observed with a packet capture; I checked both with tcpdump on the RUTX08 and with a SPAN port ("monitor session") on the managed switch where both the Teltonika and the CIsco are connected.
After changing the advertisement interval on the Cisco to 2s, both devices assume the correct role (the device with higher priority will become master).
Example config from my Cisco 1841 (I'm testing this in VLAN 11 which is configured on a HWIC-4ESW module in the Cisco, and I'm using VRRP group id 11 on both the RUTX08 and the c1841):
ip address 192.168.11.253 255.255.255.0
vrrp 11 ip 192.168.11.1
vrrp 11 timers advertise 2
vrrp 11 priority 90