To disable the AutoAnalyzer feature in Premiere Elements 12, please open the program to the Elements Organizer 12 phase or, in the Premiere Elements Editor workspace, click on the Organizer tab at the bottom of that interface to open to the Elements Organizer 12.
In the Elements Organizer 12 interface, go to Edit Menu/Preferences/MediaAnalysis and disable all the options there (including ones specifically labelled AutoAnalyzer Options).
I work with the AutoAnalyzer disabled and use on the "on demand" basis only when obsolutely necessary. My "on demand" is right clicking the file's thumbnail in Project Assets and then selecting Run AutoAnalyzer.
I find leaving AutoAnalyzer active gets me my videos split into clips and stacked.
What is it supposed to be doing? This Barbara Brundage article may be of interest in that regard
Photoshop Elements 12 and Premiere Elements 12 are standalone programs, each coming with the Elements Organizer 12. When they are on the same computer, they share the same Elements Organizer catalog.
If you have not already, you might want to look into the newly released 12.1 Update for Premiere Elements 12 and the Elements Organizer 12. See Help Menu/Updates within the program.
Please review and then let us know if any questions or clarification needed.