Files unable to decrypt when removing Dell Encryption

I am trying to decrypt a system, while troubleshooting another issue.  I've found that 0 out of 3 systems that I've tried to decrypt have finished successfully - the decryption service is still running after weeks, months.

Here's some errors from the logs.... (from various systems, all have similar errors)

[05.16.17 08:11:54] SDE Decrypt Service - DecryptSweep_CheckDecryptFile(): Error calling DeviceIoControl(CREDCEF_ChkPathEncr) for file "C:\System Volume Information\{2c601cfa-303d-11e7-9dfa-e4a471bd4977}{3808876b-c176-4e48-b7ae-04046e6cc752}", win32Err = 5

[05.16.17 08:11:30] SDE Decrypt Service - DecryptSweep_CheckDecryptFile(): Error calling DeviceIoControl(CREDCEF_ChkPathEncr) for file "C:\pagefile.sys", win32Err = 32

[05.16.17 08:12:23] SDE Decrypt Service - DecryptSweep_CheckDecryptFile(): EncryptDecryptFile("C:\Windows\Temp\CEFD029.CEFD029.CEFD029.CEFD029.CEFD029.CEFD029.CEFD029.CEFD029.CEFD029.CEFD029.CEFD029.CEFD029.CEFD172.CEFD7cf.CEFD5a5.ood_stream.x86.en-us.dat.TMP.TMP.TMP.TMP.TMP.TMP.TMP.TMP.TMP.TMP.TMP.TMP.TMP.TMP.TMP") failed, win32Err = 998 [SDE]

[07.31.17 15:41:15] SDE Decrypt Service - DecryptSweep_CheckDecryptFile(): EncryptDecryptFile("C:\Program Files (x86)\Microsoft Office\root\Office16\ADDINS\Microsoft Power Query for Excel Integrated\bin\CEFD784.CEFD8be.CEFD823.CEFD784.CEFD8be.CEFD321.Microsoft.WindowsAzure.StorageClient.dll.TMP.TMP.TMP.TMP.TMP.TMP") failed, win32Err = 998 [SDE]

[07.31.17 15:41:15] SDE Decrypt Service - DecryptSweep_CheckDecryptFile(): EncryptDecryptFile("C:\Program Files (x86)\Microsoft Office\root\Office16\1033\CEFD029.CEFD029.CEFD029.CEFD029.CEFD029.CEFD7a9.OWSHLP10.CHM.TMP.TMP.TMP.TMP.TMP.TMP") failed, win32Err = 998 [SDE]

[07.31.17 15:41:08] SDE Decrypt Service - DecryptSweep_CheckDecryptFile(): Error calling DeviceIoControl(CREDCEF_ChkPathEncr) for file "C:\swapfile.sys", win32Err = 32