Please set the posting process to post through to the G/L, not just post to. If unable to make that the default, please allow an option.
For all other main sub ledgers, when I create a batch (as I do in Fixed Asset GL Posting routing) and select 'Post', the batch posts through to the G/L.
Currently in fixed assets, I have to generate the batch, post the batch in Fixed Assets & the subsequently go post the batches again in the G/L.