No, AES-SIV is just newer. There are currently no published weaknesses (to my knowledge).
There are however a few practical inefficiencies:
- the fixed locations of the SIV (/ authentication tag) can be a bit tricky to work with, as it means that the wrapped key data cannot be stored in the same place as the unwrapped key data;
- it's a two pass protocol, which requires a bit more work.
The other wrapping methods have been standardized as well and are not broken in any significant way. So there is no big incentive to shift to SIV, even if it has the deterministic integrity protection property.
Many keys are stored in key stores rather than being wrapped individually (although combined approaches are used as well). A key store is likely to have no need for a deterministic algorithm such as SIV.
So it's an educated guess that AES-SIV is not implemented much due to lack of (commercial) interest.
Note that we're still in the process of moving out SHA-1 in favor of SHA-256. There is a very clear reason to do so, and SHA-3 is already out as well. The security field is not known for speedy transitions, even though it is just half a century old.
EDIT > 2yrs later: currently there seems to be a bit more interest to avoid the dire consequences of IV reuse for CTR mode and all authenticated ciphers (CCM, GCM, EAX etc.) that rely on it. That may speedup the use of AES-SIV and it's sibling, AES-GCM-SIV.