I had several problems with the Audacity 3 versions.
I do commend the compacting into one file but that will never help fixing anything.
I found that by using the 3 version in Windows 7 Pro 32 bit outputting multiple files in wav or compatible forms for Audacity 2 versions then running Windows XP SP3 to put them back together once again worked perfectly.
I would avdise knowing the bit rate etc. before you output the individual tracks so you know what to use when putting them back together.
As an Engineer I can tell you that using twice the sample rate of the highest frequency will be fine so if one can hear up to 16Khz than 32 sample rate will be fine. 44.1k seems to be the new standard even if you have dogs.
I do NOT have dogs so I will likely reinstall the older version of Audacity in Windows 7 and worry about the Win10 stuff even though I do have Audacity on Win10.
So DOGOFF with the 3 versions. They keep xchanging the latency settings.
Smell bad!! Slobber too much!!!