For what it's worth, I start getting this error mysteriously in my PowerShell Toolkit based automation when I add progress/messages event handler to my Analyze task (called using "FileBasedProject.RunAutomaticTask" method).

Running pre-translation / analysis tasks...
Error: Unexpected exception when completing task 'Analyze Files': Invalid number of analysis bands.
Sdl.ProjectAutomation.Core.ProjectAutomationException: Unexpected exception when completing task 'Analyze Files': Invalid number of analysis bands. ---> Sdl.ProjectApi.ProjectApiException: Unexpected exception when completing task 'Analyze Files': Invalid number of analysis bands. ---> System.ArgumentException: Invalid number of analysis bands
   at Sdl.ProjectApi.AutomaticTasks.Analysis.AnalysisTask.SetAnalysisWordCounts(AnalysisContentProcessorX processor, ITranslatableFile translatableFile, WordCounts newWordCounts)
   at Sdl.ProjectApi.AutomaticTasks.Analysis.AnalysisTask.UpdateFileAnalysisStatistics(AnalysisContentProcessorX processor)
   at Sdl.ProjectApi.AutomaticTasks.Analysis.AnalysisTask.TaskComplete()
   at Sdl.ProjectApi.Implementation.TaskExecution.ContentProcessingTaskImplementation.TaskComplete()
   --- End of inner exception stack trace ---
   at Sdl.ProjectApi.Implementation.TaskExecution.ContentProcessingTaskImplementation.TaskComplete()
   at Sdl.ProjectApi.Implementation.AutomaticTaskExecuter.Execute()
   --- End of inner exception stack trace ---
Task Analyze Files not completed.
Unexpected exception when completing task 'Analyze Files': Invalid number of analysis bands.

When I remove the event handler from the RunAutomaticTask call (and that's the ONLY change in the script!), everything works just fine (analysis reports are created and contain correct data):

Running pre-translation / analysis tasks...
Task Analyze Files successfully completed.