Interesting that you got a response already as a Platinum. I sent a TTU yesterday about my bag being lost/delayed on both my outbound and return flights (non-stop DTW-MSP with no connections) and got this reply, as a Base Member:

We are experiencing an increase in our email volume and we appreciate
your patience. If you have requested a response to your email, you
should hear from from us within 14 business days.

Note that it doesn't say "14 days" (a common way to say "about 2 weeks") but rather "14 business days" (an oddly precise and possibly misleading way to say "about 3 weeks").