It found the problem was compounded by the force's outdated and disjointed IT systems, one of which was at least 25 years old.
But it also praised the "high quality training" offered by the force.
The review was launched in response to a complaint of racial discrimination made by PC Jim Davies in 2014.
It also recorded another allegation of "racist language" used by an officer in the same year, which was reduced from gross misconduct to misconduct.
And it raised concerns over "potentially derogatory" Powerpoint slides used in training, which referred to "good breeding potential" and women who "expect to be hit".
The authors of the review highlighted the absence of an "ethnicity recording system" that could properly track people from the Gypsy, Roma and traveller (GRT) communities.
They said this problem was made worse by "elderly" IT programs, including a DOS-based system at least 25 years old, and a version of Windows that Microsoft no longer supported.
It said: "Without clear ways of tracking GRT populations it is impossible to effectively consider the equality impact on these populations."
The review was carried out between June 2014 and May 2015 and was led by Professor Margaret Greenfields of Buckinghamshire New University, as well as PC Davies who founded the the Gypsy, Roma and Traveller Police Association.
Prof Greenfields said the force had "fully accepted" the review's recommendations and praised it for "seeking to go far beyond tokenism or minimum standards of community engagement".
A total of 40 crimes were identified in which members of the GRT community were involved.
Thames Valley Police must improve how it records data on Gypsies, Roma and travellers "as a matter of urgency", an independent review has said.