How to randomly select one of the two pictures and export text/graphic questions?

I am using Qualtrics to design an experiment. Basically, I have a list of 29 issues and want to assess participants' attitudes toward each issue (using loop & merge to achieve this). After assessing participants' attitudes toward each issue, I will provide either a pro-attitudinal or counter-attitudinal picture in a random order to see how participants' attitudes will change after seeing each picture (using "advanced randomization-random subset" to achieve this).
However, the randomization of pro-attitudinal or counter-attitudinal pictures through "random subset" doesn't work...It randomizes the valence of pictures across participants but not the valence of pictures a single participant will see during the experiment. Also, the valence of each picture that participants see is not included in the data export as it is a text/graphic question.
Does anyone have any suggestions about these questions? Thank you so much for your help!