Dealing with "Responses in Progress"?

Is this B2B? In that case, the anti-spam filters may be clicking into your survey link in the emails and making it look like the response is in progress even though the invitee hasn't even opened (or seen) the email.
We are having major deliverability issues this month - went down from 10% to less than 2% response rate because emails aren't even getting to customers through their spam filters because Qualtrics IP addresses are on global blacklists that are being referenced by these companies.

Hi - yes, this is B2B. You might be onto something with the anti-spam filters. One other data point - it looks like almost all the respondents marked as "in progress" are from only one or two companies...which makes me think those specific companies' spam filters got triggered, which would lead to what you described. EDIT: one other data point I just noticed - the start time and last activity on these surveys is exactly the same time...which leads me to believe these "in progress" survey responses didn't start from human intervention.
We didn't send the surveys through Qualtrics - I created unique URLs for each customer, imported that list into our marketing automation platform (HubSpot) and then sent the surveys from there. That would imply we're not getting caught by the issue with Qualtrics IP addresses. I'm waiting to get open/click/bounce rate data out of HubSpot, so that might give me a clue.
Thanks for your answers!

HubSpot also employs a shared IP model, unless you are using an SMTP relay approach. So they have have reputation issues as well.
We are investigating implementing an SMTP relay for Qualtrics sends so we can have a dedicated IP address for our company.

For incomplete responses in a completely anonymous survey (via anonymouse link), is there a way to send a follow up email for those who haven't completed it?