Once the strides are on land they shake then one pushed back in lava they walk like the lava is ice and slide around and they don't sink in lava as they are found!!! in the lava!!!
I understand they have basalt legs and they walk in lava but they sink their legs in according to the update, As of now they are pretending as lava is ice and they slide around on lava source or flowing blocks!!!!

This only seems to happen to me in Hardcore, And putting on saddle does nothing
Creative spawned and natural spawned seems fine in all other gamemodes!!!!
Tested with multiple Hardcore worlds and this does happen in everyone of them!