"No index available.." error when querying XATTR array index

This issue is going to be a blocker for SyncGateway + GSI setup as it uses similar index structure to query SG-originated attributes

to reproduce:

1) insert a document with following xattr object:
  "_sync": {  "channels": { "channel-1": 1 } }

2) create index
CREATE INDEX `ixChannels2` ON `bucket-1`((all (array (`op`.`name`) for `op` in object_pairs((((meta().`xattrs`).`_sync`).`channels`)) end)))

3) run query:

SELECT meta().id
FROM `bucket-1`
WHERE any op in object_pairs(meta().xattrs._sync.channels) satisfies op.name = "channel-1" end

The query works as expected up to build 5.5.0-1756. On build 5.5.0-1757 it fails with " "No index available on keyspace..."

Fails only when indexing the xattrs. If put this object in doc body it works fine.

Changes in build 5.5.0-1757:

https://github.com/couchbase/query/commit/d72a02d389a46dae20afea0e207fb9e869b99cff

[+] d72a02d MB_27706 Token index fields may not be formalized properly when query executed multiple times