"Our investigations have revealed that [there are] several transactions made by the company which require further investigation," the progress report said.
Creditors agreed to the request and the extension was granted in July.
The administrators also confirmed that they have submitted a report on the conduct of Mid Group's directors to the Department for Business, Energy & Industrial Strategy, as required by law. The contents of this report are confidential.
The administrators have so far received £2.7m in claims from 22 of Mid Group's creditors, although they estimate the company owed an additional £22.4m.
The offsite specialist, which had seen rapid growth since it was founded in 2014, collapsed last year. Mid Group's latest accounts showed it had a turnover of £55.7m and had made losses of £2.7m in its last full year of operation.
At the time it went into administration, the firm had been contracted to build residential schemes in Slough and Bristol, worth £41m and £32m respectively.
