For reasons unknown to us, Pure made changes in their REST API where they started returning arrays of data where once individual objects were returned for some REST API calls. Newer versions of OCI support the Pure firmware that introduced these changes. I strongly suspect that the Pure array that is failing is running a newer firmware than the one that is being discovered successfully
OCI 7.1.x is in extended support, if it is supported at all.
I would as a general recommendation, strongly encourage upgrading to OCI 7.2.7 or 7.3.1 where the OCI Pure datasource has support for the firmware you are running.
Failing that, you should try installing the most recent Data Source Service Pack for OCI 7.1.x
OCI engineering resolved this Pure issue with engineering issue ICI-4138. This resulted in a datasource patch *after* OCI Data Source Service Pack 4 for 7.1.x was released.
If this were your only data source issue, I would say:
Install SP4 for 7.1.2 as discussed above
Call support to open an issue, say that you need the 7.1.x patch for ICI-4138.
However, it sounds like you are doing a variety of data source tasks, and doing that with data source code that is ~18 months old is very tricky as you likely have upgraded other, non-Pure, device firmware in that time