Validation Error -on uploadApiDocument, The number of Pre-Verify results does not match the number of documents that were sent for verification.

We've started getting this error message on test cases that have previously worked with the same JDK version. Can you point me in the right direction?

com.silanis.esl.sdk.internal.EslServerException: Could not upload document to package. Exception: HTTP POST on URI https://sandbox.e-signlive.com/api/packages/zcL8xvxsiguXCQi6ZPFMxdYTGHc=/documents resulted in response with status code: [400, Bad Request]. Optional details: {"name":"Validation Error","message":"The number of Pre-Verify results does not match the number of documents that were sent for verification.","parameters":{"errorException":"PreVerifyDocumentCommand : (DE) Code 6 - PDF Library threw an exception with error message [Expected a dict object.]. "},"code":400,"messageKey":"error.validation.documentPreVerifyInvalidResponseNumberError"}

2025-08-15 15:45:33,491 INFO  [stdout] (default task-393)     at com.silanis.esl.sdk.service.PackageService.uploadApiDocument(PackageService.java:348)