Sorting issue in MP client-only

[mindsolve]

I am observing strange sorting behaviour while trying to sort an inventory on a Vanilla-MP-server. It seems like it is in some kind of repetion here? Every 4th sorting step is the same as before.

See the following screenshots: (each image is after sorting the large chest one time)

System info:

• Minecraft 1.15.2
• Forge 1.15.2-31.1.34
• invtweaks-1.15.2-2.0.3.jar from CurseForge
• System: Window 7 x64
• Java: 1.8.0_51
• Other mods installed:
  • journeymap-1.15.2-5.7.0beta1
  • ReAuth-1.14-3.8.0
  • jei-1.15.2-6.0.0.2