Oracle PLS-00201: Identifier must be declared tips - intermittent

A call is going from my WebApi to Oracle 12g to retrieve data. Below is the connection string.

Persist Security Info=False;User ID=[userid];Data Source=(DESCRIPTION=(ADDRESS=(PROTOCOL=TCP)(HOST=[host])(PORT=1521))(CONNECT_DATA=(SERVER=dedicated)(SERVICE_NAME=[servicename])));Pooling=true;Min Pool Size=1;Connection Lifetime=180;Connection Timeout=10000;Incr Pool Size=5;Decr Pool Size=5;Max Pool Size=100;PASSWORD=[password]

In one of the testing environments, it is failing with the below error on the second call. The first one happens successfully. The connection is being closed explicitly in code.

Oracle.ManagedDataAccess.Client.OracleException (0x80004005): ORA-06550: line 1, column 7: PLS-00201: identifier '[proc name]' must be declared ORA-06550: line 1, column 7:

If I disable pooling, by setting Pooling=false, it works every time. Also, this connection string exists in our PROD environment and it's working fine there as well. The only difference is that Connection Timeout is set to 180 in PROD.

The fact that it's failing after the second time consistently is puzzling me. Please help.

Thanks, Arun