Sometimes I receive `null` progress value in a task metadata

[MisRob]

Summary

Sometimes I receive null progress value in a task metadata which breaks progress modal interface:

Screenshot of tasks API response data when it happened to me:

I haven't been able to reproduce reliably yet though I was seeing it quite often for publish tasks and sync tasks (it can actually also be seen on the recording attached to #2952)

[MisRob]

Possibly related to #2658

[pcenov]

I did not manage to replicate the above described issue while testing #3044. Quite possibly fixed.