LAST_VALUE over window in FlinkSQL

Question

I would like to run following query

SELECT key, LAST_VALUE(value) OVER (PARTITION BY key ORDER BY ts) AS value
  FROM [table]
 GROUP BY key, TUMBLE(ts, INTERVAL '5' MINUTE)

I would expect that LAST_VALUE would return last value of each time window. Instead I get

 Expression 'value' is not being grouped

Any ideas how to solve it?

---

Edit 1: Tried something like

SELECT key, LAST_VALUE(value) OVER (PARTITION BY key, TUMBLE(ts, INTERVAL '5' MINUTE) ORDER BY ts) AS value
  FROM [table]

but got instead

Unsupported call: TUMBLE(TIMESTAMP(3) *ROWTIME*, INTERVAL SECOND(3) NOT NULL) 

(also: I think this is not equivalent as now I probably get retract stream instead of append stream)