How to successfully trigger an ILA core in Vivado
EDIT



Meanwhile the problems have been resolved:


Since it was my first VHDL project, I thought it was be a good idea to combine combinatorial logic with synchronous logic in order to reduce the circuit's propagation delay. The combinatorial part had a bug in it, but it still simulated sucessfully because I didn't set the sensitivity list correctly.


Solution: avoid using combinatorial circuits whenever possible.


I was doing some calculations in compile time, which worked fine in the simulation (probably computed with 64 bit), but it led to an overflow during synthesis (probably computed with 32 bit). As a result of the overflow the optimizer removed most of my project, but it left the part that I was looking at with the debug LED un touched...


Solution: configure the module manually rather than setting it up in compile time.

This solves my core issues, but it doesn't explain the inconsistent behavior that I observed in Vivado while trying to narrow down the issue.



BEFORE EDIT



Unfortunately the issue was not resolved, but I promised to get back and report on how it went.



The short answer:


Start with a small manageable project.
Check your triggers
Make sure you're XDC file is fine.
Don't try all the instructions at once
Try to reproduce your problems on someone else's work bench if can get the opportunity.




The long answer:

The triggers were not the problem in my project. I kept cutting out pieces of my project to narrow down on the cause of the problem - till I was left with a simple counter!

So I implemented a counter driving the LED in a test project and analyzed the signal successfully. Strangely this was not reproducible with an identical counter when it was copied into the test project from my actual project!

Someone else who has the same FPGA and a slightly newer version of Vivado did exactly what I did and he successfully analyzed the project at his workbench. After sending he sent the modified test project back to me, I was able to create the debug core and it functioned as intended.

Conclusion: I ended up blaming version 2014.03 of Vivado.