neo4j index failed immediately without error - neo4j

Question

NOTE this is not the same question Neo4j Index creation fails
We have 2 types of nodes in our DB which both have a string property called text. For node A this property is not unique and for node B this property is unique. (we never explicitly have any cypher code that creates any boundary/unique conditions on anything)
We want to have 2 indexes:
create index on :A(text)
create index on :B(text)
(i am currently running those cypher queries seperately from the browser interface)
the index on :B(text) takes a minute and works fine (4 million nodes), but the index on :A(text) (1 million nodes) fails immediately and eventhough i have also tried it with the python driver with the lowest debug level and looked through /var/log/neo4j/.. i can't find any indication as to why this is failing. Judging by the documentation the fact that :A(text) is not unique should not be a problem. Does anyone have hunch where something could be wrong?
EDIT:
Neo4j Version: 3.4.8
Longest :A(text) string: 17 chars (individual words)
Longest :B(text) string: 53 chars (short phrases)
EDIT: I realize fails immediately can be a bit of a vague term, so here exactly what happens when using the browser interface...
create index on :B(text)
returns
Added 1 index, completed after 1 ms.
immediately after
:schema
returns
Indexes
ON :B(text) POPULATING
after a while
:schema
returns
Indexes
ON :B(text) ONLINE
now for A
create index on :A(text)
returns
Added 1 index, completed after 1 ms.
immediately after
:schema
returns
Indexes
ON :B(text) ONLINE
ON :A(text) FAILED