I went ahead and used Command Center and chose "update all" and then "install all". And now Strum 2 does show up in 64 bit. I now see 64 bit Plat is Lexington. I opened 32 bit and it's still Ipswich, so I installed "Platinum Instrument Collection" and Strum 2 is now installed in both 32 bit and 64 bit.
I remember last year when Command Center first came out there were a lot of requests to have it also update 32 bit Plat not only 64 bit. Unless I'm missing something here, this request has been swept under the rug. I know for a long time I'm going to have to have 32 and 64 bit both installed. I'm already using 64 bit for all new projects and after a couple of more months I'll be done with the last big 32 bit projects and can use 64 bit, except when I have to revisit a 32 bit project.