This issue is also experienced by me.
And a similar issue can be reproduced in 'one way' synonyms (Maybe it is by design, but want to know where it is mentioned).
Defined synonyms: (word1 > word2), (word2 > word3).
If I search for 'word1' it will not give results for 'word3'. I expect to have 'word1' + 'word2' + 'word3' results.
I have the following synonyms defined in the Episerver find backend:
All langugages: 123 <> training
Dutch: 456 <> training
This is the relevant part of my search code:
When the language == Language.Dutch, and the query == "123" then the UsingSynonyms is working as expected.
But when the language == Language.Dutch, and the query == "456" then the UsingSynonyms is NOT working as expected. I get 0 results. I expect to get the same results as when searching for "123".
Why is this not working as expected?