There are a number of issues that can cause this situation.
A Google search on 'Orphan MSDTC Transaction' will give you a number of references about potential causes and how to troubleshoot them.
Original author: SQL Server FineBuild 1-click install and best practice configuration of SQL Server 2017 2016, 2014, 2012, 2008 R2, 2008 and 2005. 1 Dec 2016
: now over 39,000 downloads.
Disclaimer: All information provided is a personal opinion that may not match reality.
Quote: "When I give food to the poor they call me a saint. When I ask why they are poor they call me a communist." - Archbishop Hélder Câmara