After re-opening a Sikuli file part of my script naming switched to <filename.png>

When an image is displayed with its filename instead of the thumbnail, this usually means, that the image file cannot be found in the .sikuli folder when opening it in the IDE.

Have you manipulated the folder somehow outside of the IDE?

No I have not manipulated the folder. The files are there in the same folder and visible.

Also, adding new scripts with an actual image and saving the file after re-openning file are changed to filename.png instead of the image.

Adding new scripts with image.
eg. click (actualimage)

Save file.

When I reopened the file
eg. click("423423423.png")

Make sure, your path to your .sikuli folder does not contain any blanks, special characters or even unicode characters (only ASCII-characters, numbers, hyphen and underscore).

I don't think that's the problem. But, how do you fix or correct this issue. Once the images have been changed to names eg. click("423423423.png") back to eg. click (actualimage)

If your script is named like e.g. myscript.sikuli, the respective image must be found in this folder, when Sikuli IDE opens this script (either automatically at startup or with File->Open).

There is no other way, to get the thumbnails visible.

So if you are sure, that the respective images (e.g. 423423423.png) are in the script's folder, there is some reason (I do not know which), that prevents the IDE from finding the images at reopen.