There have been added new option

"Hide already completed pictures in the gallery"

since the recent update to the version 2.26.0. 

By default the option is turned on. However if one would like all the pictures displayed in the gallery they can turn off the option the following way:

• open the app
• tap Settings (gear icon 

  ⚙️

  at the top left corner)
• switch the said option to OFF.