I just set up your configuration using the PreSonus Compressor and was not able to re-create the issue. If you look below the sample rate in the transport bar, you can see the automatic latency compensation listed. When I enable the Compressor, it jumps to 2 ms. Please be sure to click the icon of the wrench next to the letter "i" at the top left-hand corner of the screen and make sure that you have NOT checked the box to ignore Plug-in Latency. Please make sure that you are updated to version 3.5.1 of Studio One 3. If the problem persists, try removing your settings from Studio One and re-configure. Here are instructions:
1. Go to Help>Open Settings folder.
2. Copy the contents of the folder over to a folder on your desktop.
3. Close S1 and delete the contents of the settings folder with the exception of the user.license file as well as the "Extensions" folder.
4. Open S1 and go to Studio One>Options (Preferences on a Mac) to reconfigure your settings.
5. Test to see if the problem is resolved. If it is not, please feel free to copy your settings files back over from the backup that you created in step 2.
*If you are missing presets or Sound Sets after doing this, simply double-click one of your Sound Sets under Documents>Studio One>Sound Sets.
If you continue to have an issue, please submit a support ticket from within your my.presonus.com account using the "Support" tab.