Hi @Qiime2_user,
There can be skbio conflicts between older and newer versions of QIIME 2. So, the version used to train the classifier should be identical to the one within your QIIME 2 environment.
The best way to get around this is to make your own claassifiers with RESCTIPt. You can follow the main example tutorial here. The part for amplicon specific classifiers is here
Note the tutorial is not meant to be an standard operating procedure (SOP), but just a set of examples of how you can make your own classifier, as mentioned here and here.
-Cheers!