The clone workspace plugin doesn't handle matrix jobs. Running a build of a job using a workspace snapshot SCM from a matrix job results in the error:

ERROR: [ JOB ]'s most recent build matching the criteria 'Any' doesn't have a workspace snapshot attached.
Please run another build in [ JOB ] to get the workspace snapshot generated and attached.

It might be necessary to specify the matrix configuration from which to clone the workspace in the downstream job's configuration, if possible including variable interpolation from the current config. This would allow a downstream matrix job to clone the workspace from an upstream job with a similar set of axes.