Enfocer.enforce() not giving expected result when loading policy subset

[lukemsmyth]

I am trying to use domains to load only a subset of policies per these instructions. I have copied the example model.conf and policy.csv from the online editor's "RBAC with domains/tenants" example. I have a main.py to test things.

model.conf

[request_definition]
r = sub, dom, obj, act

[policy_definition]
p = sub, dom, obj, act

[role_definition]
g = _, _, _

[policy_effect]
e = some(where (p.eft == allow))

[matchers]
m = g(r.sub, p.sub, r.dom) && r.dom == p.dom && r.obj == p.obj && r.act == p.act

policy.csv

p, admin, domain1, data1, read
p, admin, domain1, data1, write
p, admin, domain2, data2, read
p, admin, domain2, data2, write

g, alice, admin, domain1
g, bob, admin, domain2

main.py

import casbin

if __name__ == "__main__":
    adapter = casbin.persist.adapters.filtered_file_adapter.FilteredFileAdapter(
        "f_policy.csv"
    )
    adapter.filter.P = ["", "domain1", "", ""]
    adapter.filter.G = ["", "", "domain1"]
    model = casbin.Enforcer.new_model("model.conf")
    filtered_enforcer = casbin.Enforcer(model, adapter)
    filtered_enforcer.load_filtered_policy(filtered_enforcer.adapter.filter)
    print(f"filtered_enforcer.get_policy(): {filtered_enforcer.get_policy()}") # prints lines 1 and 2 from `policy.csv` as a list - this is expected
    unfiltered_enforcer = casbin.Enforcer("model.conf", "policy.csv")
    print(f"unfiltered_enforcer.get_policy(): {unfiltered_enforcer.get_policy()}") # prints lines 1-4 of `policy.csv` as a list - this is expected

    request_vals = ["alice", "domain1", "data1", "read"]
    print(f"request to filtered_enforcer: {filtered_enforcer.enforce(*request_vals)} (expected True)") # prints False - this is unexpected
    print(f"request to unfiltered_enforcer: {unfiltered_enforcer.enforce(*request_vals)} (expected True)") # prints True - this is expected

Problem

As you can see from the comments above, I am not getting the expected result when calling enforce() on the filtered_enforcer. I am not sure where I have gone wrong. I would guess that I have not translated the given Go example to Python properly but I'm not sure. When I give the same request values in the online editor, I get True (expected). I would guess this is because the enforcer instance is not being filtered.

Please let me know if you can give me any insight.