Could be NTFS compression, which is LZNT1. This idea is supported by the platform and the apparent 2-byte structure, along with the byte-alignment of the actual data.
The following elements are specific to this algorithm.
Chunks: Segments of data that are compressed, uncompressed, or that denote the end of the buffer.
Chunk header: The header for a compressed or uncompressed chunk of data.
Flag bytes: A bit flag whose bits, read from low order to high order, specify the formats of the data elements that follow. For example, bit 0 corresponds to the first data element, bit 1 to the second, and so on. If the bit corresponding to a data element is set, the element is a 2-byte compressed word; otherwise, it is a 1-byte literal value.
Flag group: A flag byte followed by zero or more data elements, each of which is a single literal byte or a 2-byte compressed word.