hi all, I'm doing this topic in the english part but I already did it in french. I don't know if it's a good idea or not but I can follow both topics and if the solution comes from one of them, I'll close both and translate the solution to the other were it was not shown.

So french topic first : viewtopic.php?f=267&t=173465

I'm not that new to Kdenlive and did a couple of videos with it, mostly with version 19 and 20.

I started a project last week-end on version 20 and I wanted to add new stuff to my editing like animated written text. It's not possible in the 20 and I used DaVinci resolve to create one for a test. My editing was at its last polishing bits (adding some "annotations" with that text but the main editing was done with effects and things like that).
Then I thought "maybe there's a new version" so I checked and was pleased to find that there was a new version and there was what I needed in this version !

Great, I uninstall the 20, install the 21.08.3 and open my project. I save and have a message that says that the project was translated to the new version. So far so good, everything is here and seems to works.

I add my clips animated texts using the Title feature with the writing animation and finish my editing. Everything looks fine in the monitor so I render the project. And now I have 2 bigs problems :
- the texts are not animated (no writing animation)
- at least one of the effects is rendered wrongly as you can see on the images below.

My monitor and UI with the grid effect on the overlay video :


And the result after rendering :


I rendered using the generic MP4-H264/ACC preset. Any idea what could have happened ? Maybe an effect stack not compiled accurately or in the proper order ? What happened with the text animation ?

If you need other screenshots or videos to show you the project (or specs, logs...) I'm willing to help to resolve my issue.
And by the way, I'm not an expert on Windows but I know how to access hidden files, AppData folders... things like that (I work for a software reseller and I'm doing some technical support too so I know what you can feel on the other side and I will try not to be a burden).

edit : small video about the problem
https://youtu.be/7AJpG5eqtO8

Small improvement here, I used the Draw Box effect instead of Draw grid for my frame and it works ! And it's also probably the tool to do what I needed...

However the animated text won't render animated.

So I did a new render and I discovered that in fact all my transitions are not rendered. The texts themselves don't have a transition but maybe the way it is handled by the render engine is similar to transitions. Besides there is an image clip on the track above the one with the text that is overlapping the text.
I'll try to recreate all the transitions from scratch and maybe use another method (composite). I never did that but I'll learn new and probably better ways.