When you list with Hydra , if your default formula is different than the default formula in Sku Grid, then Hydra's default formula rules and will override each item when you list in Sku Grid.  It is recommended that you make the formula the same in both Hydra and Sku Grid before listing as a default, that way you are only overriding items when you intentionally mean to do so. 

To fix your current items in Sku Grid and set them back to your default formula, go to your Sku Grid  marketplace settings and make sure that your default formula is the way that you want it to be, if not change it.  Here are some videos on configuring your default formula in skugrid - https://www.youtube.com/watch?v=Ym2y4y2k8PI and https://www.youtube.com/watch?v=j2I5EL15Mt0

Then go to your Hydra Batch Single Lister Settings and go to the formula wizard there.  Make sure that you have Manual Override = No and enter the same exact values for each field in the formula wizard that you have for Sku Grid.  Then click Next and save the settings.  You should therefore, only be using single, batch or draft lister and never thunder lister (as thunder lister will always override because it constructs formulas differently).

To remove all override formulas from your existing items and set them back to default follow this process - https://www.youtube.com/watch?v=V7he_GenBiQ

Then finally, force reprice all of your existing items now that they are set to the default formula in Sku Grid - https://www.youtube.com/watch?v=1zK5V3D_XGg

Going forward, if you ever decide to change your default formula again, in either Hydra or Sku Grid, change it in both software first before listing again to prevent accidental overriding.