No versions appear

When creating a new installation there are no versions to choose from.

When activating the historical versions, those appear, but no more.

I can only select the four profiles I already had (newest release, newest developer update, Forge 1.12.2, OptiFine 1.8.9). Even when selecting one of them, for example the newest release, it doesn't say 1.16.5 in the version window. It's just empty.

Installing a new OptiFine version like usual does create a new installation.

Re-installing Minecraft or using the repair tool didn't help.

I've had this problem starting two days ago.