For some unknown reason, sometimes a materialized view takes more time to finish the load/update than the one defined in transaction timeout (300 seconds is the default value, and we have configured 600 seconds to try to solve the problem).
The transaction reaper will kill the update transaction. The LoadState in status table will be LOADING.
Any subsequent try to update the view will fail, since the system reads the state as being LOADING even if the system is not currently updating it.
Example log next.
The update took too long (more than 10 minutes [defined transaction timeout]):
Next I tried to update the view:
And nothing happened.