steps to reproduce:

• summon marker with some custom data
• teleport the marker into another dimension
• change the custom data of the marker
• proceed to another tick
• print the marker data

i've made the reproduction easier by making a datapack
steps to reproduce with my datapack:

• go into overworld
• run /function test:markertest
• click on "Teleport to the nether" text in chat and press enter
• click on "Print marker data" text in chat and press enter

what happens:

• after the data is modified, it will stay modified only until the end of the tick... after the tick passes, it has previous data values

what should happen:

• the data saves properly

notes:

• this also happens when the other dimension's chunks are forceloaded