Usually the suction does not reach the whole slab, an opening was missed, the fan is wrong for the soil, or the test was not run correctly. Ohio proposals must state a guarantee and its conditions or explain why there is none, so start there.
More detail
Check the test first. The post-mitigation test should run between 24 hours and 30 days after activation, under closed-house conditions, in the same spot as the original test, with the system running, and not during a windstorm. If the test holds up, look at the design. Ohio's standards call for a communication test wherever the material under the slab is unknown; slabs poured in sections, interior footings, and dense clay can block suction, and a second suction point often solves it. Openings that could not be sealed must have been disclosed in writing. A sump with a working pump should not be the primary suction point. Old stone foundations in Clintonville and German Village are the classic hard case. See the Clintonville stone basement scenario.