Some of my single-player worlds don't show up. The files are all still on my laptop, I haven't messed with them, and I'm running vanilla 1.17. I can usually play on these worlds for anywhere from 3 days to several weeks, but most new worlds I've created have this issue. I've seen no pattern. I get a huge chain of fatal errors when I load up the game output now, the same cause on all of them:

"Caused by: java.util.zip.ZipException: invalid distance too far back"

I've tried backups but had no luck.

"Exception reading ... Zelot 2\level.dat
z: Loading NBT data
at na.a(SourceFile:434)
at na$1.a(SourceFile:71)
at na$1.b(SourceFile:57)
at nk.a(SourceFile:108)
at nk.a(SourceFile:75)
at nk.a(SourceFile:32)
at nk.a(SourceFile:26)
at dib.a(SourceFile:229)
at dib.a(SourceFile:178)
at dib.b(SourceFile:157)
at eek.a(SourceFile:93)
at eek.<init>(SourceFile:85)
at eeh.b(SourceFile:63)
at eap.b(SourceFile:387)
at dvo.a(SourceFile:986)
at eau.d(SourceFile:144)
at dwz.c(SourceFile:40)
at dwt.a(SourceFile:16)
at dwx.a(SourceFile:121)
at dxw.a(SourceFile:27)
at eau.a(SourceFile:311)
at dvp.b(SourceFile:94)
at eap.a(SourceFile:490)
at dvp.a(SourceFile:94)
at dvp.c(SourceFile:165)
at aqu.execute(SourceFile:101)
at dvp.b(SourceFile:165)
at org.lwjgl.glfw.GLFWMouseButtonCallbackI.callback(GLFWMouseButtonCallbackI.java:36)
at org.lwjgl.system.JNI.invokeV(Native Method)
at org.lwjgl.glfw.GLFW.glfwPollEvents(GLFW.java:3101)
at com.mojang.blaze3d.systems.RenderSystem.flipFrame(SourceFile:165)
at dpq.e(SourceFile:310)
at dvo.f(SourceFile:1139)
at dvo.e(SourceFile:730)
at net.minecraft.client.main.Main.main(SourceFile:217)
Caused by: java.util.zip.ZipException: invalid distance too far back
at java.base/java.util.zip.InflaterInputStream.read(InflaterInputStream.java:164)
at java.base/java.util.zip.GZIPInputStream.read(GZIPInputStream.java:117)
at java.base/java.io.BufferedInputStream.fill(BufferedInputStream.java:244)
at java.base/java.io.BufferedInputStream.read1(BufferedInputStream.java:284)
at java.base/java.io.BufferedInputStream.read(BufferedInputStream.java:343)
at java.base/java.io.DataInputStream.readFully(DataInputStream.java:201)
at java.base/java.io.DataInputStream.readUTF(DataInputStream.java:615)
at java.base/java.io.DataInputStream.readUTF(DataInputStream.java:570)
at na.b(SourceFile:423)
at na$1.a(SourceFile:68)
at na$1.b(SourceFile:57)
at na.a(SourceFile:428)
... 34 more"