iOS 13.5.1 - Mail App will not launch contacts on composing new message

I am pleased to say this issue has now been resolved. I woke up this morning with the intention of deleting the whole Contacts App but I edited the App by deleting an entry and then reinserting the contact. The Mail App now works fine. I am a happy bunny. Thank you all who have taken the time to read the posting.

Perhaps I should add that the iPhone SE is for my wife. I have an iPhone XS which is also running 13.5.1 without any problem which makes me wonder whether the answer lies in the SE's settings. I have checked the SE's settings to ensure they follow the XS and they appear to do so. It is only my wife's contact details the Mail App recognises in the new SE which is in her own name. I have even now resorted to a full restore on the SE but the issue remains. I cannot understand why the Mail App on the XS works fine but not on the new SE. I am hoping there is someone out there in the community who is far more learned than I am on these matters. Thank you.

Thank you Haliday987. Something I didn't think of but having done what you suggest I'm afraid the issue remains.