Hey, with respect to this, there is a hot fix available when the Report Designer Add-In doesn't show up as available in Excel. Just had this on 2017 and the fix does work.
https://support.na.sage.com/selfservice/viewdocument.do?noCount=true&externalId=67230&sliceId=1&cmd=displayKC&dialogID=237618&docType=kc&isLoadPublishedVer=&stateId=237826&docTypeID=DT_Article&ViewedDocsListHelper=com.kanisa.apps.common.BaseViewedDocsListHelperImpl