@KelseyLeerkes I usually follow the below steps to isolate something like this.
1) from the SQL server, check the ODBC connection in ODBC manager to ensure file counts are returned and reasonable,
2) in SQL, test the linked server and ensure it can retrieve values from Sage 100 (select * from openquery(MAS_ABC, 'Select * from GL_Account') ) where MAS_ABC is the name of your linked server. (If this fails, pay particular attention to the bitness of the SQL server and your ODBC drivers. They must be the same. 64 bit SQL requires 64 bit Providex ODBC drivers on the SQL server to read from Sage 100.
3) ensure that you have proper security rights with domain-level user accounts running the SQL service. The user that the SQL service is operating under will be the account trying to gain access to the Sage 100 data on a remote server so make sure it has the rights to do so.
4) ensure the BizNet user has rights to access data in SSRS. This should be set by the BizNet deployment tool provided you ran the tool while logged in with Domain Admin rights.
BizNet has excellent support. If you open a service ticket with them through the partner portal and tell them the service is down, they typically have someone with you in 30 minutes or less and will do the troubleshooting for you. Leverage the resource. It's free to all resellers. This is an area where you absolutely do not have to walk alone in the wilderness.