I noticed that your using an older version FAB 3000 V7.
Note: FAB 3000 V7 is several years old and there have been many updates to the ODB++ importer since then. If possible I would recommend trying FAB 3000 V8 (instead of V7). You can also try our free ODB++ Viewer called DFM Now V8. If DFM Now V8 loads your ODB++ than using FAB 3000 V8 will resolve the import issue. https://www.numericalinnovations.com/pages/dfm-now-free-gerber-viewer