Thanks for the report, and sorry for the late reply. I'm not involved with this sidemod myself, but do know that there's a community patch that fixes a few issues.
Link: https://cdn.discordapp.com/attachments/ ... .0-all.jar
This release is unofficial and largely untested, so proceed at your own risk. I'm leaving this ticket open for a proper resolution, but this unofficial build may help in the mean time.
Note to anybody reading this in the future: This release is for Pixelmon 7.0.7, with the newest official sidemod release being 1.0.2. If there's a newer official version, use that!