Context Menu items missing, shortened when more than 15 files selected
If you wish to remove this restriction, you can remove it as follows. Open regedit and navigate to the following registry key: Here create a new DWORD, MultipleInvokePromptMinimum The Default value is 15 (decimal). The permissible range is 1 – 16 (decimal). If you wish to reduce this figure, give it a lower value. If you wish to completely remove this restriction, give it a value ’16’. A value of 16 is interpreted as “unlimited”. The registry change will go into effect after logging off and back on, or after restarting Windows Explorer.
Source: KB2022295. Check this if you cannot Print more than 15 files at a time in Windows 10/8/7.
