error when creating logical replication slot

Hi all,
I am implementing logical replication and today during some final tests
before implementing it to the production I have got this error when logical
replication slot on master was created.

NOTICE: 2019-01-28 09:08:22.081007+00: logical replication slot xxxxx does
not exist - creating...
ERROR: snapshot reference 0x55a52a898340 is not owned by resource owner
TopTransaction
CONTEXT: SQL statement "SELECT pg_create_logical_replication_slot('xxxxx',
'pgoutput')"

In previous tests I always created logical replication slot in the same way
and never had any error. For explanation - I create logical replication
slot separately otherwise command "create subscription" from replica hang
indefinitely if I try to create LRS as part of it (tested several times).

I tried to google for this error but did not find anything which would feel
relevant to the context.

Could someone please explain to what does this mean? I cannot afford to
have errors on production.

Many thanks

Josef Machytka
Berlin