I followed your process and produced the same result as you, 2000 files showing in explorer.
I copied the files from my computer using the aws cli into this folder "/To Required/LAS/8-November-2019-Depot" and could only see 1000 files in this folder.
After a number of test's removing all possibilities I think I have solved the problem but it still seems like a bug.
I copied the files into this folder "/ToRequired/LAS/8-November-2019-Depot" and I can now see all 2000 files.
Seems like the space in the folder name was causing this problem.
In the original logs I replaced a company name with Required and did not leave a space in the name.
i was able to replicate the bug by creating 2000 files with a space in the file name. For /L %%i in (1,1,2000) do fsutil file createnew "test %%i.txt" 1
then i did two mounts, pointing to the same folder, using two different versions of rclone.
rclone-v1.50.1.exe mount wasabieast2:testnumfiles2000 b:\mount\rclone-v1.50.1\
and rclone-v1.50.2-085-g2dddcc52-fix-3799-s3-nextmarker-beta-windows-amd64.exe mount wasabieast2:testnumfiles2000 b:\mount\1.50.2-085-g2dddcc52-fix-3799-s3-nextmarker-beta-windows-amd64\
and then copied the files to one of the the mounts