Curently this issue can be worked around by using commands on the placed block such as "/data modify block ~ ~-1 ~ normal_config.spawn_potentials set value [{data:{entity:{id:"minecraft:spider"}},weight:1}]". this bug is spawn egg specific
have the same problem with 1.10-pre-1, 1.10-pre-2 and the official 1.10 version.
Curently this issue can be worked around by using commands on the placed block such as "/data modify block ~ ~-1 ~ normal_config.spawn_potentials set value [{data:{entity:{id:"minecraft:spider"}},weight:1}]". this bug is spawn egg specific