There might be a few things you may check or do:

1. Ensure that match threshold in project settings is low enough to show matches. Perhaps set it to 50%? The text may seem almost the same to you but if there are a lot of different new tags, they might throw off the matching routines.

2. Ensure that the TM you are using is in the latest format. You might need to upgrade.

3. If a TM is used for a long time it might need reindexing

4. Your TM may be somehow damaged. Then it might be a good idea to export the TM to TMX, create a brand new blank TM and re-import the TMX to this newly created TM.

Let me know if any of these worked for you.

There might be a few things you may check or do:

1. Ensure that match threshold in project settings is low enough to show matches. Perhaps set it to 50%? The text may seem almost the same to you but if there are a lot of different new tags, they might throw off the matching routines.

2. Ensure that the TM you are using is in the latest format. You might need to upgrade.

3. If a TM is used for a long time it might need reindexing

4. Your TM may be somehow damaged. Then it might be a good idea to export the TM to TMX, create a brand new blank TM and re-import the TMX to this newly created TM.

Let me know if any of these worked for you.

I tried the first and the third, nothing changed (apart from the fact that most things were 100% matches).
The second does not apply, they are upgraded and I don't even have the option to click on.

This would be a 100% match and it does not show up! Everything is enabled.
AnyTM because there are 3 standard varieties of German, and I don't want to separate them since it's just about very few words that are different.

Everything is enabled, I even removed lots of TMs that are not as closely related, but still it doesn't work. Why would I even use a CAT tool at this point?

Felicita Ratti 

The TMs work reliably. Any chance you made a mistake setting up the language resources? With AnyTM, it would be possible to have your TM work the wrong way around, say IT-DE instead of DE-IT. Just trying to think what might be the issue here.

Daniel

The flags are showing the correct direction.
Apart from that, I now realised that, although I have enabled source editing, said source editing is NOT working.
It seems like the program is not working at all, to be honest.

You have just revealed the key piece of the information - you are using the AnyTM engine which is probably significantly different from connecting a local TM the regular way. If I were you, I would export all these different varieties of German to separate TMX files then create a new TM and import (consolidate) all these TMX files into a single newly created TM.

If it is not possible to import and consolidate some varieties German into your new TM, use notepad (or notepad++) to open the relevant TMX files and then find and replace the language designations as needed, so that TMX is accepted on import.

You admit yourself that the different varieties of German have hardly any differences between them, then why keep separate TMs for them and use AnyTM?

I have always used this feature with no issue at all, for years. So why should it be the "key piece of information"? Trados is not working, there must be some issue, and Trados should solve it.

Felicita Ratti 

Can you just confirm that you are looking for a 100% TM match?  I ask because the screenshot you showed seems to be the Concordance window and you don't have anything in the search box so I would not expect to see any results in there.

Paul 

The top part of the screenshot seems to show the TM results window. I wonder whether this setting is on:

Daniel Hug 

You're right... I missed that she had separated the windows.  I think it would be helpful to see the expected TU in the TM itself and verification that the TM in this project is the same as the TM with the expected TU.  Obvious things, but otherwise we might be looking for a problem where there isn't one.