Added your useful plugin to another site where SearchWP is used to index PDF files. This promptly appeared on the Dashboard:
SearchWP has detected a potential (not guaranteed) action/filter conflict with pre_get_posts caused by an active plugin or the active theme.
This is simply a preliminary detection of a possible conflict. Many times these detections can be safely dismissed
If (and only if) you are experiencing issues with search results not changing or not appearing, the following Hooks (put in place by other plugins or your active theme) may be contributing to the problem:
If you believe there to be a conflict (e.g. search results not showing up): use this information you can determine how to best disable this interference. For more information please see this Knowledge Base article.
I haven't seen any changes in queries or results, but I thought I'd pass this on.