Hi akj,
Thank you for your post. We understand how frustrating it is to face this problem with the invoices and how your business is affected. This is not the experience we want to provide our customers. We strive hard to provide a seamless experience for our customers. We sincerely apologize for the inconvenience this issue has caused you.
Regarding your concern, the current workaround is to resize the logo or re-create your customized form. Then try again to send the invoices to your clients. If they're still experiencing the red line when viewing the invoices, please let us know so we can raise and alert the relevant team to this error.
We thank you for your patience and understanding in this matter.
Cheers,
Princess