When there is a persistence config in VPP which is loaded at startup and this config will create a tap port wit subinterface, then every read operation on interfaces-state will fail.
VPP startup conf:
vppctl tap connect tap-admin-vpp
vppctl create sub tap-0 0
vppctl set int ip addr tap-0.0 192.168.1.101/24
vppctl set int state tap-0 up
vppctl set int state tap-0.0 up
HC bug in log attached
The TapName is null for the subinterface