The information you ask for is routinely published and therefore available in the public domain; however, I have provided it below for ease of reference.
IPP population as at 30 June 2019:
IPP first releases April 2018 to March 2019 inclusive:
Between April 2018 and March 2019 inclusive, a total of 356 IPP prisoners were released following recall from the community. This data is not separated by gender.
As with any large-scale recording system, administrative IT systems are subject to possible errors with data entry and processing.