There is a bug in the foam alley portion of Iron Horse right before the 4th boss where if after completing this section you reset the raid for any reason when you get back to that section it appears to have saved the progress of the train from the last run and will cause a failure to occur. this also then makes it so that running on the right side is sometimes impossible as you will not be able to break the water boxes.

Example if you are allotted 60 seconds to complete foam alley and took 45 seconds on your previous run you will only have 15 seconds to complete the section the second run and might not be able to break the water on the right.