I'm having a very frustrating time where I am building emails in standard and then having issues sending proofs.
I have links within the email that include personalisation (segment and campaign coding). When I send a first proof it works fine but if I make any changes whatsoever to the email (including adding more test profiles) it will no longer send any proofs and error out. The error says the segmentation step before does not exist. Adobe support said its a personalisation issue but that's all.
Please share more details around the personalization done in the email and the workflow/ segmentation steps. The issue would indeed be related to personalization/ customization as I don't seem to face the same challenge.