My wife and I each have separate treasury direct accounts. I added both accounts, and they both seemed to add ok. But unlike most other institutions with multiple accounts, it shows as two separate institutions both called Treasury Direct, rather than having one institution with multiple accounts associated with it. Moreover, in my spreadsheet where both are included, only the first one I added shows up anywhere, including the Accounts tab and the Balances tab.
If you added these after already syncing to a spreadsheet you may need to go into the console and select the accounts to be added to your spreadsheet. This help article should direct you to the right steps.
Just curious if @bentyre1’s suggestion worked or if it is still an issue. My wife and I had separate Treasury Direct accounts for our I Bonds and recall something similar to what you described. That issue, plus their clunky 2FA, led me to unlink the accounts and add them as Manual Accounts. All we needed was our balance updated monthly, though.
I have a slightly different issue with Treasury Direct. I have multiple accounts within my main login for paper I-bonds converted to be electronic. When I login myself to TD I can navigate and see the holdings for all of my accounts but Tiller only sees the main account. I assume this is Yodlee issue but it would be nice if I didn’t have to use a manual account to track this. I filed a ticket but was told this wouldn’t be fixed.