Running job preview shows invalid data

When new file is being imported via data-import, the running section should display progress, number of records and date when it was started. Instead it shows incorrect data - "NaN" for numbers and "Invalid date" for date.
See the screenshot attached. Please note that this behavior is inconsistent - the same file can be imported and all the info in running section would be correct.

Probably an issue with backend, per Sasha and Igor. Leave in backlog for now, and see if we can reproduce it.