A few months, maybe a year ago, when I was playing Batman Origins, I noticed that I wasn't getting notifications for my achievements.
I looked for the solution but nothing worked, then I played many games without achievements and I thought that maybe with the new updates the problem should be solved.
But now I've played a game with achievements again and although I get them they don't appear to me while playing, which makes it difficult to know if I completed the game, achievement I exit the game.

I have the options, but I still don't see achievement notifications when I have it and I want to see it again like before.
How can I fix this?
I want to solve this, please

1. Click the "More" button next to the Play button, and choose Manage Installation, then Configure.
2. On the Features tab, check if Overlay is available and enabled.

If Overlay is grayed out, the feature isn't supported by the game. You can check the overlay fixes thread for a possible solution.

If Overlay is enabled but it doesn't work anyway, it's probably due to conflicting software on your computer like RivaTuner, MSI Afterburner, or whatever else tries to hook an overlay into games.

As Ice_Mage pointed out, there are some games that have broken overlay support, but if it is not supported at all (so isn't mentioned on the store page nor on galaxy) you can try to force enable it globally.

You can also look at some tests I made with unsupported titles down below

https://www.gog.com/forum/general_beta_gog_galaxy_2.0/galaxy_overlay_tests_and_reports_for_unsupported_titles

I have disabled all programs with overlay, gog overlay still doesn't work