Ensembl id to GeneSymbol with biomart
It looks like you were using an old annotation. The problematic IDs you posted existed in the GRCh37 annotations, but don't in the most recent GRCh38 annotation. For that reason they were excluded. The IDs that have - as symbols don't have associated symbols, but are present in the database.

To use an archived version in biomart:

mart = useDataset("hsapiens_gene_ensembl", useEnsembl(biomart="ensembl", version=84))


That's an example for release 84.