Product image placeholders cannot be configured from admin

[dkorpar]

Preconditions (*)

1. Magento 2.2.6

Steps to reproduce (*)

1. Install Magento 2.2.6
2. Go to Stores / Configuration / Catalog / Catalog / Product Image Placeholders
3. Choose any placeholder (e.g. Small), choose a file and save configuration

Expected result (*)

1. Image preview available below the 'Choose file' button
2. Image uploaded
3. core_config_data has a row with path catalog/placeholder/image_small_placeholder and value to a file path
4. Product images have an uploaded placeholder image

Actual result (*)

1. No image preview below the 'Choose file' button
2. Image uploaded
3. core_config_data has a row with path catalog/placeholder/placeholder and value to a file path
4. Product images have a default placeholder image

[magento-engcom-team]

Hi @dkorpar. Thank you for your report.
To help us process this issue please make sure that you provided the following information:

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• Information on your environment
• Steps to reproduce
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Please make sure that the issue is reproducible on the vanilla Magento instance following Steps to reproduce. To deploy vanilla Magento instance on our environment, please, add a comment to the issue:

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where $VERSION is version tags (starting from 2.2.0+) or develop branches (for example: 2.3-develop).
For more details, please, review the Magento Contributor Assistant documentation.

@dkorpar do you confirm that you was able to reproduce the issue on vanilla Magento instance following steps to reproduce?

• yes
• no

[magento-engcom-team]

Hi @engcom-backlog-nazar. Thank you for working on this issue.
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Hi @dkorpar thank you for you report, this issue has already fixed by this commit #18160.