Hang on - where's the main conflict?
I've recently been struggling with a very strange problem in my writing: I can't find the main conflict in my novels. This has inspired quite a bit of thought and reflection on exactly what a main conflict is, but I'm still just as stumped, if not more so. I'm not new to writing, so this issue is quite baffling.
Backstory: To understand where I'm coming from, you have to know that I'm a plotter, meaning I plan my novels out almost to the scene before writing a word. It's a good thing I do, because it filters out problems like this before I run into them while writing.
In addition to this, and this is very important, I center my novels around a main message, or theme. Literally everything in my novel has a purpose. Nothing is random. Everything works to tell that message in some way. This isn't just some aspect of writing that I can change, either; this is how I write. I want my novels to have meaning.
Conflict: Until recently, I've always seen conflict as a struggle between two things, be they choices or just opposite directions/paths. Because I've been developing novels that seem fine but appear to have no main conflict, I've quickly realized this can't be the case. Because of this, I've arrived at the conclusion that main conflict would be more properly described as an obstacle in the way of whatever is trying to be attained: the goal (arrived at by envisioning a novel where the main conflict is to get through a maze). That still doesn't help me though.
The Problem: Based on the above definition, I was able to finally identify the main conflict of my current WiP. However, I am still unable to identify the main conflict of typical mystery novels.
When I was struggling to define main conflict, I used the example of a typical detective/mystery novel. The goal is to catch whoever did the crime, or maybe prove he's guilty. There's nothing really standing in the way of that, unless you count the detectives' simple ignorance of all the facts. And that hardly seems like it could be the main conflict to me. Obviously there are mystery novels with twists on the basic design where the main conflict is more obvious, but what about the generic typical detective/mystery story? Where is the main conflict?
Question: Either my understanding of main conflict is completely off (which I doubt), or there's something I'm just not seeing. Could you please explain where I'm going wrong here? Where's the main conflict?
Important Note: My novels seem fine, meaning they seem to have a main conflict. Because of this, I don't think the problem is a lack of main conflict. I think the problem is that I simply can't define that main conflict (which I need to do in order to develop it).
This question is slightly similar to this one. While the answer to that question was helpful by listing different kinds of conflict, I don't feel that it answered my question, as I still can't determine the main conflict of typical detective/mystery novels.
Answer: After some thought inspired by my own reflections and Lauren Ipsum's answer below, I believe the reason I can't find the main conflict in my example is because it does not have a theme. Every scenario I've thought of that includes a theme results in a definable main conflict.