The most recent update to the paid version (v0.6.1) included a complete rework of the mining wing. It's so substantial, and feeds into so many bits of content which will be important moving forward that I decided to reset everyone's progress in that area to ensure that they see the new stuff.
This is the second time I've ever done this (the first being resetting the handful of actions in the Plateau for its rework in v0.6.0), and it isn't likely to happen much, if at all, in future versions.
Really glad you're enjoying it though, and thank you for supporting me :)