problems reopening visio saved docs on linux

Hi
I am using Libreoffice 6.0.1 when I open *.vsdx and then save as either .odg or fodg.

I cannot reopen the ,odg or .fodg

.odg

Read Error.
Format error discovered in the file in sub-document content.xml at position 2,3385(row,col).

.fodg
General Input/output error.

Works fine on the Mac.

Cheers Vin