Error when opening a file

[r-groeneveld]

I try to open a file from a folder on icloud, and get a error message "Fout bij het openen van" with the long path and filename. In the textbox error message the filename is truncated, i.e. it does not show the full filename. Never had a problem with long filenames until now with TextMaker. What can I do?
PS: contacting the helpdesk via help function inside TM did not yet give me an answer/reaction. Thanks!