cPanel Email Deliverability - suggested SFP record includes 'undefined'

I recently transferred a cPanel account from a legacy WHM server to a new server running WHM 90 using the WHM Transfer Tool. On the new server I'm looking at the Email Deliverability area in cPanel, with a view to adding DKIM and SPF records to the domain DNS, which is held off the server in AWS Route 53. Currently in the cPanel account there is no DKIM key (presumably this is something that is not transferred as part of the WHM transfer process, but no problem, I can generate a new one) and for some reason the SPF value cPanel suggests to me includes undefined. v=spf1 +a +mx +ip4:111.222.333.444 +include:spf.mtasv.net ~undefined
From what I've researched the typical value here is ~all. What's causing the undefined value, and what's the appropriate value for the SPF record?