We had a similar experience in our school district. DS9 was not accepted into G/T programming based on OLSAT but was accepted after administration of the WISC-IV. So I do think its possible to test HG without passing the OLSAT.
I will note one surprise we encountered from the additional testing. One assessment showed a distinct nonverbal strength, the other showed a definite verbal strength. I was hoping for one test that captured all his abilities accurately (by my definition anyway) but that has been elusive. And it can create a little trouble in advocating for him when the school makes placement decisions based on one test vs. the other.
Best of luck to you!
