Experience bar shows zero after teleporting in spectator to another dimension

I was investigating a source of lag on my multiplayer server and teleported between dimensions. When I returned to normal play, I noticed that my experience bar had shown no experience at all.

How I achieved this behavior:

• begin in survival mode with some level of experience
• change into spectator mode
• teleport to a player in the nether (`/tp <self> <player in the nether>`)
• (at this step, I ran a few commands, in particular killing items that were getting built up while someone was afk)
• teleport to a player in the overworld (`/tp <self> <player in the overworld>`)
• return to survival mode

At this point I noticed my experience bar showed zero. I was a little disappointed (this had happened before and I thought I had lost my experience). It was night in Minecraft, I went to sleep, and when I woke up the experience bar showed the correct number of levels.

I would expect the experience bar to show the correct level, as long as I'm in survival mode.