Write Enable Tapes

You can't change expiration date of volume, but rather of ssids. However, my question would be what do you really want? Title suggests you want to write enable them (if they are full, you can't until they are recycled). Then you say you wish to change expiration date (which is not related to volume state) and they you say you recycled tape. If tape is recycled now and you want it to have that appendable NW will take care of that automatically by relabeling tape when needed. However, if you recycled tape that was not suppose to be recycled you might loose data you would still need so the key question is what you want and what you did exactly.

Ideally what I need is to take the 20 or so virtual tapes that I mistakedly marked for a two year expiration date and allow them to be recycled (rewritten to). I've labled them as recycle but they are still unable to be written to.

If you recycled tapes then they are could be reused by NW once they are required. Until then NW will use appendable tapes for particular pool. Once a new tape will be required and no appendable would be available, NW will take one eligible for recycling (recycled by you) and will relabel that tape automatically. By default that will happen for tapes in pool which is required. If this is required for different pool then either enable such operation from pool properties or manually relabel tape for required pool.