RGB Inconsistencies in InDesign CC 2018 (Windows 7)

Issue

The following issue happens although I am not even trying to convert to CMYK. This is strictly within RGB (and I did not see any forum entries that addressed this issue – if it exists, please steer me in the right direction):

In InDesign, I use the Color Picker to create an RGB Color with values 29, 112, 124.
Using a color picker tool, I can verify that the color is correct:

Color Picking Tool

Swatch

When I create a swatch with this chosen color, the colors are supposedly as inserted, but measuring them with the color picker tool, the color has changed to 34, 111, 123:

Using the color

Filling a rectangle with the color is wrong, too (both when using the color picker or the swatch) – the color is 34, 111, 123:

Exporting as JPEG

Exporting as a JPEG, the color changes even more (to 35, 111, 123):

The issue does not happen when…

.. I use for example RGB 0, 100, 100
.. I use Adobe Suite CS6 (on another computer)

What I have tried without success:

Deleting the InDesign cache.
Using other color settings in Bridge/InDesign.
I double checked: there is no CMYK color in my document, there are no transparencies.

Using a spot color (which does not really make sense if I am not even intend to print) does not help

Checked in Photoshop CC 2018 with a new document: the color also changes.

Color and Document Settings

Although I cannot imagine that the color settings have to do with it (I am not trying to convert between RGB and CMYC, I am not trying to print), here are the color settings:

Bridge Color Settings

InDesign Color Settings

Document Setup

Can anyone point me in the right direction? Am I doing something wrong or is it maybe a bug in the Adobe Suite CC 2018? Maybe it is resolved in the 2019 version?

Thanks in advance,

Britta