Are you looking at datasets that were created many years
ago (or with the old software), or are you looking at datasets
created with the current binaries?

It is possible that it is only the warning that is new.

Where the bucket datasets saved from a single execution
of 3dDeconvolve, or via 3dDeconvolve -xrestore, or maybe
some other way?

Since we don't actually know how you created these datasets,
it is difficult to say much.

In any case, heed the warning. Do not make datasets with
multiple data types. If you have such datasets, convert them
(to either floats or scaled shorts), e.g.

3dcalc -a dset.mixed+orig -expr a -datum float -prefix dset.float

- rick