Stranded Deep has been updated to version 1.10 today by Beam Team Games. You can find out the complete patch notes for this update from here.
The game has been plagued with multiple issues since the last patch that added multiplayer was released for it. These issues are gradually being addressed and the latest patch is another step in the direction to fix the new issues occurring since the last update. The patch notes for this mention falling through the ground and connecting online bug fix.
Stranded Deep Update 1.10 Patch Notes
- Fixed an issue with animals and items falling through the ground
- Fixed an issue where connecting to online sessions in specific regions would fail
The developers have confirmed that the interaction issue will be patched in an update on October 15, so this appears to be finally out today. If you are still facing issues, try turning wildlife off and then saving and load the game. Turn it back on again to resolve the issue.