Compare https://musicbrainz.org/ws/2/artist/b04f4c77-9ede-44b6-ba4d-832bc85dd82b?inc=aliases&fmt=json and https://musicbrainz.org/ws/2/artist?fmt=json&query=arid:b04f4c77-9ede-44b6-ba4d-832bc85dd82b

A lookup gives, for example:

"locale":"en"
"name":"Reina Tanaka",
"primary":true,
"sort-name":"Tanaka, Reina",
"type":"Artist name",

and

"locale":null
"name":"Tanaka Reina",
"primary":null,
"sort-name":"Tanaka Reina",
"type":null,

whereas a search gives

"begin-date":"",
"end-date":"",
"locale":"en",
"primary":"true",
"sort-name":"Tanaka, Reina",
"type":"Artist name",
"value":"Reina Tanaka"

and

"begin-date":"",
"end-date":"",
"locale":"",
"primary":"false",
"sort-name":"Tanaka Reina",
"type":"",
"value":"Tanaka Reina"

The differences I can see:

• lookup has "name", search has "value"
• lookup doesn't have empty begin/end dates, search does
• lookup doesn't quote "true", search does
• lookup uses "primary": null, search uses "primary": "false"
• lookup uses "null", search uses a quoted empty value

The "name" vs "value" one definitely seems problematic.