Time: 19:35 GMT-5
Context: Useless Selenium Club, Cyberian Tundra biome (ice and snow cubes)
Game Details: Bovine Buildmaster
Character Details: Ice Sage lvl 11 (tried with my Gunslinger lvl 30 too)
Expected: Place blocks behind me with the mount in the ice and snow cubes
Observed: Nothing happens

Repro Steps:
1. Equip Bovine Buildmaster
2. Go to building mode using Bovine Buildmaster
3. Choose 1st slot of inventory
4. Walk with the mount
5. Nothing happens