As ChrisK asked:
We do not even know what Vivaldi combination you have. Is it just the DAC? Is it DAC plus Upsampler? Is it DAC plus Network Bridge?
Have you updated all of the firmware including Mosaic? It would help if you would kindly just reveal the version numbers of the firmware you are currently using which is really what Chris K was asking for.
The last issue I recall relating to muting between tracks was this ( but it does not appear to reflect your circumstances) :
However it does prompt me to ask what the DAC is displaying when your issue occurs. Are you seeing " No Audio"?
One thing that I can say now, however, is that dCS equipment currently has no support for gapless replay with MQA encoded programme. I am assuming, however, that as you say the problem occurs with standard files too this is not related to your particular issue though it could be confused with it. I am also now assuming that the issue is not just occurring with MVK files. The reason I asked the question earlier was because if it was just MVK files that would suggest corrupted files at the Tidal end of things. Such things do happen.