Reproducible error after killing Thunderbirds on the Island of fire map

Each time after killing Thunderbirds which guard a shipyard, they remain on the map and no further action can be performed because of Uncaught error. The hero becomes grey.
E.g. I cannot enter any town, move (by this hero), end turn. Can change heroes though, view their info and move with other heroes (but they are not displayed on the map after a move, visually remaining on the initial position).
Tried to load game, load not the last save, make several fights before fighting Thunderbirds, refresh a page - result always the same.

Log: Uncaught Common.ClientError {name: 'HeroWO.RPC.ClientError', message: undefined, responseCode: null, responseData: undefined, stack: 'Error\n at new Common.ClientError (https://herow….net/databanks/sod/herowo.min.js?19dts4:86043:35)'}message: undefinedname: "HeroWO.RPC.ClientError"responseCode: nullresponseData: undefinedstack: "Error\n at new Common.ClientError (\n at Sqimitive.errorObject (\n at ...

What exactly did you do to trigger it?

kill Thunderbirds - fight end successfully.

On which map it happened?

Island of fire

A screenshot or video would be fantastic.

Lol - “sorry, new users cannot upload attachments”
What for I recorded a video…
I can also provide my save for testing.

Reproduced on the same map with other hero with another fight. So it is not dependent on a specific enemy
http 204 No Content
and the same story - page refresh and reload game doesn’t help to fight this specific enemy, although others can be fought.