Query can result in wrong when index key is DNF transformed

CREATE INDEX `ix1` ON `default`(ISSTRING(name)) WHERE ISSTRING(name);

INSERT INTO default VALUES("k01",{"name":"abc"});

select 1 from default USE INDEX (ix1) where ISSTRING(name) = true and ISSTRING(name);

returns 0 results.
Reason is "index_projection": {},
This happens due to ISSTRING(name) index key is DNF transformed but actual query never DNF transformed so could not decide if the expression is index key dependent.

select count(1) from default where ISSTRING(name)=true AND ISSTRING(name) ;
not using index aggregates and also gives wrong results