InDesign makes vector graphics and text thicker when I perform seemingly unrelated actions.

[OH! Graphics]

Hello!

I am trying to do two things: Place a background image on my layout, and add Object Effects (Outer Glow, Drop Shadow, etc.) to one of my placed EPS graphics.

However, I'm experiencing an extremely strange issue. Whenever I try to place a PNG image anywhere on my layout (I could use JPG and EPS, but I'd rather fix the issue than dance around it) or when I try to give anything an Effect, ALL of the text and vector graphics on my layout are automatically given a thicker, bolded appearance, despite being unrelated to the actions I am attempting to perform. The added thickness is not a stroke, as the "flavor text" still has a 0 stroke. No objects are not grouped, and each individual element on my layout are on separate, locked Layers as to avoid accidental edits to objects I'm not currently working with. It isn't a visual discrepancy, as the issue persists on an exported PDF file.

I haven't encountered anything this puzzling before. Examples of my issue are below. Help is very much appreciated! 

P.S. I'm not sure which Topic this goes in, because I am unsure if it is a Bug, and the problem isn't exclusively with the Type.

[OH! Graphics]

Please excuse the typo:

"No objects are not grouped" should be: "No objects are grouped". 

[JonathanArias]

May I ask why are you working with .eps? You should be placing a .ai file instead. 

[OH! Graphics]

I never encounter any problems when using .eps over .ai, other than not being able to edit the vector's layers directly in InDesign. That doesn't bother me since I work more comfortably using the native program. I use .eps mostly because I still have to share these individual vectors with my friends that don't use Adobe. 

Regardless, I tried using .ai files instead of .eps and my problem still persists, so there's no reason to go further into my preferences here.