Hello everyone, I'm new to Kdenlive and this forum, so I hope I'm doing everything right, otherwise please let me know.

I'm trying to make a really simple video, using some pictures and some videos. I had managed to put something together and I saved my project. Unfortunately, when I opened my project to start working on it again, I could see the clips and the audio in the tracks, but in the project monitor everything was black and I could only see a white text that said "invalid". I thought I had saved the project the wrong way, so I started anew. After finishing my video for the second time, I rendered it and it came out okay. Then I saved my project again, opened it, and, just like the previous time, I can't see anything, and for every clip it shows in the project monitor the "invalid" text.
I don't understand what I'm doing wrong, I've tried to search the web and this forum for a solution but I couldn't find anything.

Any help is greatly appreciated.
Thank you

Do the clips match the project settings? On which OS you work? Kdenlive version?

I work on Linux Mint 18.2, and the Kdenlive version is 16.04.3. How do I check if the clips match the project settings?
Thanks for replying!

As you work on Mint 18.2 try to download the Appimage 18.04.1b direct from here: https://files.kde.org/kdenlive/release/

You have to turn the Appimage into an executable file. Select the Appimage -> properties -> Perrmisson -> click on “Allow execute this file”.

It could be that MLT, KDE, QT and other component in Kdenlive 16.04.3 doesn't match with Mint 18.2 anymore.