Urgent-Tier 2 visa application status meaning

[koko88]

Any expert opinion for the different status:
My application status was 'Delayed-Further verification required'
and now changed to- Work in Progress.
What is the difference between these 2?
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13th April: I have submitted my documents and biometrics taken.
2nd May- I got an email from UKVI asking for missing documents
4th May: I have submitted the missing scan of the document and on the same day I got a reply since your application is not straightforward can not be completed within the specified time.
10th May- I called UKVI number and the status was: Delayed: More verification/inquiries required.
29th May-I again called the UKVI number and the status was- Work in Progress.

What should I assume? Any expert please share your thoughts.