Table Relationships with Different Data Sources

Hi, I just recently got introduced to and starting using the OneLake catalog as a data source for my current sales data. I have a fact table that has all my sales for 2025 in the OneLake and then I have other dimension tables that are imported from excel files. Some of those diemsnion tables include product and customer information. 

I am trying to create a sales report that can be sliced/filtered based on product information, customer information, and the sales representative. But I noticed that my 2025 sales table wasn't adhering to these slicers. I have some other fact tables that are imported from excel files and not in the Onelake, and those aren't having any problem being filtered by my slicer visuals. I'm guessing this has to do with a problem in the relationship that is established or with the OneLake data source itself? I'm not quite familiar with the way OneLake works how it effects data modeling but I did notice that the connection for the relationships I created are defined by a different type of line. 

They're almost like parenthesis attached to the end of the relationship lines.

This is what my 2025 sales data is going. All the prices are the same for all the segments, when it should be doing what the Total YTD Sales 2024 column is doing. 

Can anyone tell me what the difference this line means compared to a regular many-to-one relationship? And how I can fix it so my Onelake data source is being filtered/sliced properly?