There's a new mandatory, 5.2.0.0! It fixes a bug with new solo cruncher's pending rewards being reset as well as adding a bunch of other features. It will also help get you off some of the forks that have been happening lately. You must upgrade to it by block 2197000 which is ~11 days away.
For more information and the full changelog, see https://www.reddit.com/r/gridcoin/comments/lv0pia/gridcoin_5200mandatory_hilda_release/