I asked this in the Canadian SPG Card thread, but this thread is probably more appropriate:

Does anybody know by experience if transferring AMEX Membership Rewards Points to the combined Marriott program (i.e. after August 2018) still counts as a qualifying activity?

I transferred to SPG prior to the merger of the programs in August 2018, and those transfers show up under my Marriott account as qualifying activities (i.e. my 2 year expiry date is from the last transfer I did).

Also, is it just me or is your points expiry date only explicitly stated on the Marriott app? I can only find the dates of my last qualifying activities on the website.