This bug affects the FIR Compiler v6.1 and v6.2 and will be fixed in the next release of the FIR Compiler.
There are multiple ways to work around it.
This problem has been fixed in the FIR Compiler v6.2 Rev2 patch. To obtain the patch, see (Xilinx Answer 42260).
Please see (Xilinx Answer 29138) for a detailed list of LogiCORE IP FIR Compiler Release Notes and Known Issues.