Hi @SpaghettiSam , You’ve added a preflight profile, but you also have to add the rules you want to use and set their flags. Here‘s a JS example, where I’ve added two functions for creating the profile and its rules:
//Make a new Preflight Profile
var pf = makePreflight("TestPreflight");
//add rules to the profile, 2nd parameter is the rule constant string
var tr = makeRule(pf, "ADBE_TransparencyUsage")
tr.flag = PreflightRuleFlag.returnAsError;
var ml = makeRule(pf, "ADBE_MissingModifiedGraphics")
ml.flag = PreflightRuleFlag.returnAsError;
/**
* Makes a new Preflight
* @ param preflight name
* @ return the new preflight
*/
function makePreflight(n){
if (app.preflightProfiles.itemByName(n).isValid) {
return app.preflightProfiles.itemByName(n);
} else {
return app.preflightProfiles.add({name:n});
}
}
/**
* Makes a new Preflight Rule
* @ param preflight name
* @ param the preflight rule constant name
* @ return the new preflight rule
*/
function makeRule(pf, n){
if (pf.preflightProfileRules.itemByName(n).isValid) {
return pf.preflightProfileRules.itemByName(n);
} else {
return pf.preflightProfileRules.add(n);
}
}

Here’s a list of the rule name constants:
ADBE_BlankPages
ADBE_BleedSlug
ADBE_BleedTrimHazard
ADBE_CMYPlates
ADBE_Colorspace
ADBE_ConditionIndicators
ADBE_CrossReferences
ADBE_FontUsage
ADBE_HiddenPageItem
ADBE_ImageColorManagement
ADBE_ImageResolution
ADBE_InaccessibleUrlLinks
ADBE_InteractiveContent
ADBE_LayerVisibility
ADBE_MissingFonts
ADBE_MissingGlyph
ADBE_MissingModifiedGraphics
ADBE_MultiPageSizes
ADBE_OPI
ADBE_Overprint
ADBE_OversetText
ADBE_PageCount
ADBE_PageSizeOrientation
ADBE_Registration
ADBE_ScaledGraphics
ADBE_ScaledType
ADBE_SmallText
ADBE_SpanColumns
ADBE_SpellCheck
ADBE_SpotColorSetup
ADBE_StrokeRequirements
ADBE_TextOverrides
ADBE_TrackedChange
ADBE_TransparencyBlending
ADBE_TransparencyUsage
ADBE_UnresolvedCaption
ADBE_WhiteOverprint