Limits of optimization tool

[yc736]

I am trying to run an optimization and when I used a small test dataset it worked perfectly. However now when I run a larger dataset it stalls at 36%, last run I left it running 30-45minutes without it finishing.

Is there a limit to the variables/fields I can include in an optimization? Is there any workaround to get the tool to run?

For context, I am supplying variations of "products", want the optimizer to choose a combination of these products to maximize the expected return. For example, product 1 has variant 1-1,1-2,1-3,1-4, etc. 

In one attempt I made random edits to the constraints (just changed numbers up and down) and the model ran but since then it keeps failing. Not sure if my problem is the size or something in the underlying data.

Really appreciate any advice here, not sure what else to try.