The Trump campaign would not comment on the payment dispute to the Washington Post.
"This is an administrative issue that we're resolving internally," spokesman Jason Miller told the Post.
Fabrizio, a veteran GOP pollster, was hired by the Trump campaign in May at the recommendation of Paul Manafort, who has since left the campaign.
Reports throughout the campaign suggest that Fabrizio has expressed concern to Trump about about his style and that he's been dismissed by Trump and other members of the campaign.
The pollster reportedly warned Trump in August that attacks like the one on the Khan family could cost him the election. A CNN report later that month noted that Fabrizio was largely in the dark about the campaign's plans. The Huffington Post reported that Trump promoted Kellyanne Conway to campaign manager partially because he did not like when Fabrizio presented bad poll numbers and told the nominee to make adjustments.
New York Magazine's Gabriel Sherman reported recently that Trump's son-in-law, Jared Kushner, who is a close ally to the GOP nominee, had dismissed Fabrizio's plans to conduct focus groups at the convention.