Mixed mode cluster returns wrong results

Install couchbase-server-5.1.0-5552.x86_64

Configure Data/Index service

Install on another node couchbase-server-6.0.2-2368.x86_64

Join the earlier cluster with data/Index/Query Service

Create default bucket

insert into default values("k01",{"date":"2019-07-11T00:00:00"});

create index ix1 on default(STR_TO_MILLIS(date));

create index ix2 on default(STR_TO_MILLIS(date));

     -- Each index goes on different node.

select META().id FROM default WHERE STR_TO_MILLIS(date) = STR_TO_MILLIS("2019-07-11T00:00:00");

        -- When query uses index on 5.1.0 node IndexScan returns 0 results.