Check that the SYSIBM setting in Options is correct. Also check that all aliases are defined in SYSIBM.SYSTABLES, and that they are denoted with an "A" in the TYPE column.
Often this problem is caused by an out-of-sync catalog cache location. If this is the case, rebuild the catalog cache. If this is not the case, or if rebuilding the catalog cache does not correct the problem, contact Micro Focus Technical Support.