Hi @DCristino and welcome to the Community! 
We are thrilled to have you join us! 
Thank you for asking the Community!
I’d like to ask clarifying questions, please:
1. Has the name of the file or the link of the file been updated in OneDrive?
2. Is the image still in public sharing mode?
3. When you tried to add the signature in HubSpot again, did you get an error message? If yes, which one?
The more info, screenshots (without sensitive/confidential information), and details you can provide, the better the Community can assist.
I also wanted to invite a couple of subject matter experts to this conversation: Hi @LouiseHare, @FCorbaci and @Mike_Eastwood do you have suggestions to help @DCristino, please?
If anybody else has anything to add and/or share, please feel free to join in the conversation 
Thanks so much and have a great weekend!
Best,
Bérangère